test: beta reduction tests for grind

A small boost before #6691 made `modifyState` more complex, a larger
boost after.

src/CMakeLists.txt

@@ -699,12 +699,12 @@ else()
 endif()
 
 if(NOT ${CMAKE_SYSTEM_NAME} MATCHES "Emscripten")
-  add_custom_target(lake_lib ALL
+  add_custom_target(lake_lib
     WORKING_DIRECTORY ${LEAN_SOURCE_DIR}
     DEPENDS leanshared
     COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make Lake
     VERBATIM)
-  add_custom_target(lake_shared ALL
+  add_custom_target(lake_shared
     WORKING_DIRECTORY ${LEAN_SOURCE_DIR}
     DEPENDS lake_lib
     COMMAND $(MAKE) -f ${CMAKE_BINARY_DIR}/stdlib.make libLake_shared

src/Init/Data/Array/Basic.lean

@@ -455,7 +455,7 @@ def mapM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (f : α
 /-- Variant of `mapIdxM` which receives the index as a `Fin as.size`. -/
 @[inline]
 def mapFinIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m]
-    (as : Array α) (f : Fin as.size → α → m β) : m (Array β) :=
+    (as : Array α) (f : (i : Nat) → α → (h : i < as.size) → m β) : m (Array β) :=
   let rec @[specialize] map (i : Nat) (j : Nat) (inv : i + j = as.size) (bs : Array β) : m (Array β) := do
     match i, inv with
     | 0,    _  => pure bs
@@ -464,12 +464,12 @@ def mapFinIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m]
         rw [← inv, Nat.add_assoc, Nat.add_comm 1 j, Nat.add_comm]
         apply Nat.le_add_right
       have : i + (j + 1) = as.size := by rw [← inv, Nat.add_comm j 1, Nat.add_assoc]
-      map i (j+1) this (bs.push (← f ⟨j, j_lt⟩ (as.get j j_lt)))
+      map i (j+1) this (bs.push (← f j (as.get j j_lt) j_lt))
   map as.size 0 rfl (mkEmpty as.size)
 
 @[inline]
 def mapIdxM {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (f : Nat → α → m β) (as : Array α) : m (Array β) :=
-  as.mapFinIdxM fun i a => f i a
+  as.mapFinIdxM fun i a _ => f i a
 
 @[inline]
 def findSomeM? {α : Type u} {β : Type v} {m : Type v → Type w} [Monad m] (f : α → m (Option β)) (as : Array α) : m (Option β) := do
@@ -588,7 +588,7 @@ def map {α : Type u} {β : Type v} (f : α → β) (as : Array α) : Array β :
 
 /-- Variant of `mapIdx` which receives the index as a `Fin as.size`. -/
 @[inline]
-def mapFinIdx {α : Type u} {β : Type v} (as : Array α) (f : Fin as.size → α → β) : Array β :=
+def mapFinIdx {α : Type u} {β : Type v} (as : Array α) (f : (i : Nat) → α → (h : i < as.size) → β) : Array β :=
   Id.run <| as.mapFinIdxM f
 
 @[inline]

src/Init/Data/Array/Lemmas.lean

@@ -93,7 +93,7 @@ theorem size_eq_one {l : Array α} : l.size = 1 ↔ ∃ a, l = #[a] := by
 
 /-! ### push -/
 
-theorem push_ne_empty {a : α} {xs : Array α} : xs.push a ≠ #[] := by
+@[simp] theorem push_ne_empty {a : α} {xs : Array α} : xs.push a ≠ #[] := by
   cases xs
   simp
 
@@ -174,10 +174,6 @@ theorem mkArray_succ : mkArray (n + 1) a = (mkArray n a).push a := by
   apply toList_inj.1
   simp [List.replicate_succ']
 
-theorem mkArray_inj : mkArray n a = mkArray m b ↔ n = m ∧ (n = 0 ∨ a = b) := by
-  rw [← List.replicate_inj, ← toList_inj]
-  simp
-
 @[simp] theorem getElem_mkArray (n : Nat) (v : α) (h : i < (mkArray n v).size) :
     (mkArray n v)[i] = v := by simp [← getElem_toList]
 
@@ -1383,8 +1379,6 @@ theorem filter_eq_push_iff {p : α → Bool} {l l' : Array α} {a : α} :
   · rintro ⟨⟨l₁⟩, ⟨l₂⟩, h₁, h₂, h₃, h₄⟩
     refine ⟨l₂.reverse, l₁.reverse, by simp_all⟩
 
-@[deprecated filter_map (since := "2024-06-15")] abbrev map_filter := @filter_map
-
 theorem mem_of_mem_filter {a : α} {l} (h : a ∈ filter p l) : a ∈ l :=
   (mem_filter.mp h).1
 
@@ -2050,6 +2044,11 @@ theorem flatMap_toList (l : Array α) (f : α → List β) :
   rcases l with ⟨l⟩
   simp
 
+@[simp] theorem toList_flatMap (l : Array α) (f : α → Array β) :
+    (l.flatMap f).toList = l.toList.flatMap fun a => (f a).toList := by
+  rcases l with ⟨l⟩
+  simp
+
 @[simp] theorem flatMap_id (l : Array (Array α)) : l.flatMap id = l.flatten := by simp [flatMap_def]
 
 @[simp] theorem flatMap_id' (l : Array (Array α)) : l.flatMap (fun a => a) = l.flatten := by simp [flatMap_def]
@@ -2096,7 +2095,7 @@ theorem flatMap_singleton (f : α → Array β) (x : α) : #[x].flatMap f = f x
 theorem flatMap_assoc {α β} (l : Array α) (f : α → Array β) (g : β → Array γ) :
     (l.flatMap f).flatMap g = l.flatMap fun x => (f x).flatMap g := by
   rcases l with ⟨l⟩
-  simp [List.flatMap_assoc, flatMap_toList]
+  simp [List.flatMap_assoc, ← toList_flatMap]
 
 theorem map_flatMap (f : β → γ) (g : α → Array β) (l : Array α) :
      (l.flatMap g).map f = l.flatMap fun a => (g a).map f := by
@@ -2135,8 +2134,317 @@ theorem flatMap_eq_foldl (f : α → Array β) (l : Array α) :
     intro l'
     simp [ih ((l' ++ (f a).toList)), toArray_append]
 
+/-! ### mkArray -/
+
+@[simp] theorem mkArray_one : mkArray 1 a = #[a] := rfl
+
+/-- Variant of `mkArray_succ` that prepends `a` at the beginning of the array. -/
+theorem mkArray_succ' : mkArray (n + 1) a = #[a] ++ mkArray n a := by
+  apply Array.ext'
+  simp [List.replicate_succ]
+
+@[simp] theorem mem_mkArray {a b : α} {n} : b ∈ mkArray n a ↔ n ≠ 0 ∧ b = a := by
+  unfold mkArray
+  simp only [mem_toArray, List.mem_replicate]
+
+theorem eq_of_mem_mkArray {a b : α} {n} (h : b ∈ mkArray n a) : b = a := (mem_mkArray.1 h).2
+
+theorem forall_mem_mkArray {p : α → Prop} {a : α} {n} :
+    (∀ b, b ∈ mkArray n a → p b) ↔ n = 0 ∨ p a := by
+  cases n <;> simp [mem_mkArray]
+
+@[simp] theorem mkArray_succ_ne_empty (n : Nat) (a : α) : mkArray (n+1) a ≠ #[] := by
+  simp [mkArray_succ]
+
+@[simp] theorem mkArray_eq_empty_iff {n : Nat} (a : α) : mkArray n a = #[] ↔ n = 0 := by
+  cases n <;> simp
+
+@[simp] theorem getElem?_mkArray_of_lt {n : Nat} {m : Nat} (h : m < n) : (mkArray n a)[m]? = some a := by
+  simp [getElem?_mkArray, h]
+
+@[simp] theorem mkArray_inj : mkArray n a = mkArray m b ↔ n = m ∧ (n = 0 ∨ a = b) := by
+  rw [← toList_inj]
+  simp
+
+theorem eq_mkArray_of_mem {a : α} {l : Array α} (h : ∀ (b) (_ : b ∈ l), b = a) : l = mkArray l.size a := by
+  rw [← toList_inj]
+  simpa using List.eq_replicate_of_mem (by simpa using h)
+
+theorem eq_mkArray_iff {a : α} {n} {l : Array α} :
+    l = mkArray n a ↔ l.size = n ∧ ∀ (b) (_ : b ∈ l), b = a := by
+  rw [← toList_inj]
+  simpa using List.eq_replicate_iff (l := l.toList)
+
+theorem map_eq_mkArray_iff {l : Array α} {f : α → β} {b : β} :
+    l.map f = mkArray l.size b ↔ ∀ x ∈ l, f x = b := by
+  simp [eq_mkArray_iff]
+
+@[simp] theorem map_const (l : Array α) (b : β) : map (Function.const α b) l = mkArray l.size b :=
+  map_eq_mkArray_iff.mpr fun _ _ => rfl
+
+@[simp] theorem map_const_fun (x : β) : map (Function.const α x) = (mkArray ·.size x) := by
+  funext l
+  simp
+
+/-- Variant of `map_const` using a lambda rather than `Function.const`. -/
+-- This can not be a `@[simp]` lemma because it would fire on every `List.map`.
+theorem map_const' (l : Array α) (b : β) : map (fun _ => b) l = mkArray l.size b :=
+  map_const l b
+
+@[simp] theorem set_mkArray_self : (mkArray n a).set i a h = mkArray n a := by
+  apply Array.ext'
+  simp
+
+@[simp] theorem setIfInBounds_mkArray_self : (mkArray n a).setIfInBounds i a = mkArray n a := by
+  apply Array.ext'
+  simp
+
+@[simp] theorem mkArray_append_mkArray : mkArray n a ++ mkArray m a = mkArray (n + m) a := by
+  apply Array.ext'
+  simp
+
+theorem append_eq_mkArray_iff {l₁ l₂ : Array α} {a : α} :
+    l₁ ++ l₂ = mkArray n a ↔
+      l₁.size + l₂.size = n ∧ l₁ = mkArray l₁.size a ∧ l₂ = mkArray l₂.size a := by
+  simp [← toList_inj, List.append_eq_replicate_iff]
+
+theorem mkArray_eq_append_iff {l₁ l₂ : Array α} {a : α} :
+    mkArray n a = l₁ ++ l₂ ↔
+      l₁.size + l₂.size = n ∧ l₁ = mkArray l₁.size a ∧ l₂ = mkArray l₂.size a := by
+  rw [eq_comm, append_eq_mkArray_iff]
+
+@[simp] theorem map_mkArray : (mkArray n a).map f = mkArray n (f a) := by
+  apply Array.ext'
+  simp
+
+theorem filter_mkArray (w : stop = n) :
+    (mkArray n a).filter p 0 stop = if p a then mkArray n a else #[] := by
+  apply Array.ext'
+  simp only [w, toList_filter', toList_mkArray, List.filter_replicate]
+  split <;> simp_all
+
+@[simp] theorem filter_mkArray_of_pos (w : stop = n) (h : p a) :
+    (mkArray n a).filter p 0 stop = mkArray n a := by
+  simp [filter_mkArray, h, w]
+
+@[simp] theorem filter_mkArray_of_neg (w : stop = n) (h : ¬ p a) :
+    (mkArray n a).filter p 0 stop = #[] := by
+  simp [filter_mkArray, h, w]
+
+theorem filterMap_mkArray {f : α → Option β} (w : stop = n := by simp) :
+    (mkArray n a).filterMap f 0 stop = match f a with | none => #[] | .some b => mkArray n b := by
+  apply Array.ext'
+  simp only [w, size_mkArray, toList_filterMap', toList_mkArray, List.filterMap_replicate]
+  split <;> simp_all
+
+-- This is not a useful `simp` lemma because `b` is unknown.
+theorem filterMap_mkArray_of_some {f : α → Option β} (h : f a = some b) :
+    (mkArray n a).filterMap f = mkArray n b := by
+  simp [filterMap_mkArray, h]
+
+@[simp] theorem filterMap_mkArray_of_isSome {f : α → Option β} (h : (f a).isSome) :
+    (mkArray n a).filterMap f = mkArray n (Option.get _ h) := by
+  match w : f a, h with
+  | some b, _ => simp [filterMap_mkArray, h, w]
+
+@[simp] theorem filterMap_mkArray_of_none {f : α → Option β} (h : f a = none) :
+    (mkArray n a).filterMap f = #[] := by
+  simp [filterMap_mkArray, h]
+
+@[simp] theorem flatten_mkArray_empty : (mkArray n (#[] : Array α)).flatten = #[] := by
+  rw [← toList_inj]
+  simp
+
+@[simp] theorem flatten_mkArray_singleton : (mkArray n #[a]).flatten = mkArray n a := by
+  rw [← toList_inj]
+  simp
+
+@[simp] theorem flatten_mkArray_mkArray : (mkArray n (mkArray m a)).flatten = mkArray (n * m) a := by
+  rw [← toList_inj]
+  simp
+
+theorem flatMap_mkArray {β} (f : α → Array β) : (mkArray n a).flatMap f = (mkArray n (f a)).flatten := by
+  rw [← toList_inj]
+  simp [flatMap_toList, List.flatMap_replicate]
+
+@[simp] theorem isEmpty_mkArray : (mkArray n a).isEmpty = decide (n = 0) := by
+  rw [← List.toArray_replicate, List.isEmpty_toArray]
+  simp
+
+@[simp] theorem sum_mkArray_nat (n : Nat) (a : Nat) : (mkArray n a).sum = n * a := by
+  rw [← List.toArray_replicate, List.sum_toArray]
+  simp
+
+/-! ### Preliminaries about `swap` needed for `reverse`. -/
+
+theorem swap_def (a : Array α) (i j : Nat) (hi hj) :
+    a.swap i j hi hj = (a.set i a[j]).set j a[i] (by simpa using hj) := by
+  simp [swap]
+
+theorem getElem?_swap (a : Array α) (i j : Nat) (hi hj) (k : Nat) : (a.swap i j hi hj)[k]? =
+    if j = k then some a[i] else if i = k then some a[j] else a[k]? := by
+  simp [swap_def, getElem?_set]
+
+/-! ### reverse -/
+
+@[simp] theorem size_reverse (a : Array α) : a.reverse.size = a.size := by
+  let rec go (as : Array α) (i j) : (reverse.loop as i j).size = as.size := by
+    rw [reverse.loop]
+    if h : i < j then
+      simp [(go · (i+1) ⟨j-1, ·⟩), h]
+    else simp [h]
+    termination_by j - i
+  simp only [reverse]; split <;> simp [go]
+
+@[simp] theorem toList_reverse (a : Array α) : a.reverse.toList = a.toList.reverse := by
+  let rec go (as : Array α) (i j hj)
+      (h : i + j + 1 = a.size) (h₂ : as.size = a.size)
+      (H : ∀ k, as.toList[k]? = if i ≤ k ∧ k ≤ j then a.toList[k]? else a.toList.reverse[k]?)
+      (k : Nat) : (reverse.loop as i ⟨j, hj⟩).toList[k]? = a.toList.reverse[k]? := by
+    rw [reverse.loop]; dsimp only; split <;> rename_i h₁
+    · match j with | j+1 => ?_
+      simp only [Nat.add_sub_cancel]
+      rw [(go · (i+1) j)]
+      · rwa [Nat.add_right_comm i]
+      · simp [size_swap, h₂]
+      · intro k
+        rw [getElem?_toList, getElem?_swap]
+        simp only [H, ← getElem_toList, ← List.getElem?_eq_getElem, Nat.le_of_lt h₁,
+          ← getElem?_toList]
+        split <;> rename_i h₂
+        · simp only [← h₂, Nat.not_le.2 (Nat.lt_succ_self _), Nat.le_refl, and_false]
+          exact (List.getElem?_reverse' (j+1) i (Eq.trans (by simp_arith) h)).symm
+        split <;> rename_i h₃
+        · simp only [← h₃, Nat.not_le.2 (Nat.lt_succ_self _), Nat.le_refl, false_and]
+          exact (List.getElem?_reverse' i (j+1) (Eq.trans (by simp_arith) h)).symm
+        simp only [Nat.succ_le, Nat.lt_iff_le_and_ne.trans (and_iff_left h₃),
+          Nat.lt_succ.symm.trans (Nat.lt_iff_le_and_ne.trans (and_iff_left (Ne.symm h₂)))]
+    · rw [H]; split <;> rename_i h₂
+      · cases Nat.le_antisymm (Nat.not_lt.1 h₁) (Nat.le_trans h₂.1 h₂.2)
+        cases Nat.le_antisymm h₂.1 h₂.2
+        exact (List.getElem?_reverse' _ _ h).symm
+      · rfl
+    termination_by j - i
+  simp only [reverse]
+  split
+  · match a with | ⟨[]⟩ | ⟨[_]⟩ => rfl
+  · have := Nat.sub_add_cancel (Nat.le_of_not_le ‹_›)
+    refine List.ext_getElem? <| go _ _ _ _ (by simp [this]) rfl fun k => ?_
+    split
+    · rfl
+    · rename_i h
+      simp only [← show k < _ + 1 ↔ _ from Nat.lt_succ (n := a.size - 1), this, Nat.zero_le,
+        true_and, Nat.not_lt] at h
+      rw [List.getElem?_eq_none_iff.2 ‹_›, List.getElem?_eq_none_iff.2 (a.toList.length_reverse ▸ ‹_›)]
+
+@[simp] theorem _root_.List.reverse_toArray (l : List α) : l.toArray.reverse = l.reverse.toArray := by
+  apply ext'
+  simp only [toList_reverse]
+
+@[simp] theorem reverse_push (as : Array α) (a : α) : (as.push a).reverse = #[a] ++ as.reverse := by
+  cases as
+  simp
+
+@[simp] theorem mem_reverse {x : α} {as : Array α} : x ∈ as.reverse ↔ x ∈ as := by
+  cases as
+  simp
+
+@[simp] theorem getElem_reverse (as : Array α) (i : Nat) (hi : i < as.reverse.size) :
+    (as.reverse)[i] = as[as.size - 1 - i]'(by simp at hi; omega) := by
+  cases as
+  simp
+
+@[simp] theorem reverse_eq_empty_iff {xs : Array α} : xs.reverse = #[] ↔ xs = #[] := by
+  cases xs
+  simp
+
+theorem reverse_ne_empty_iff {xs : Array α} : xs.reverse ≠ #[] ↔ xs ≠ #[] :=
+  not_congr reverse_eq_empty_iff
+
+/-- Variant of `getElem?_reverse` with a hypothesis giving the linear relation between the indices. -/
+theorem getElem?_reverse' {l : Array α} (i j) (h : i + j + 1 = l.size) : l.reverse[i]? = l[j]? := by
+  rcases l with ⟨l⟩
+  simp at h
+  simp only [List.reverse_toArray, List.getElem?_toArray]
+  rw [List.getElem?_reverse' (l := l) _ _ h]
+
+@[simp]
+theorem getElem?_reverse {l : Array α} {i} (h : i < l.size) :
+    l.reverse[i]? = l[l.size - 1 - i]? := by
+  cases l
+  simp_all
+
+@[simp] theorem reverse_reverse (as : Array α) : as.reverse.reverse = as := by
+  cases as
+  simp
+
+theorem reverse_eq_iff {as bs : Array α} : as.reverse = bs ↔ as = bs.reverse := by
+  constructor <;> (rintro rfl; simp)
+
+@[simp] theorem reverse_inj {xs ys : Array α} : xs.reverse = ys.reverse ↔ xs = ys := by
+  simp [reverse_eq_iff]
+
+@[simp] theorem reverse_eq_push_iff {xs : Array α} {ys : Array α} {a : α} :
+    xs.reverse = ys.push a ↔ xs = #[a] ++ ys.reverse := by
+  rw [reverse_eq_iff, reverse_push]
+
+@[simp] theorem map_reverse (f : α → β) (l : Array α) : l.reverse.map f = (l.map f).reverse := by
+  cases l <;> simp [*]
+
+@[simp] theorem filter_reverse (p : α → Bool) (l : Array α) : (l.reverse.filter p) = (l.filter p).reverse := by
+  cases l
+  simp
+
+@[simp] theorem filterMap_reverse (f : α → Option β) (l : Array α) : (l.reverse.filterMap f) = (l.filterMap f).reverse := by
+  cases l
+  simp
+
+@[simp] theorem reverse_append (as bs : Array α) : (as ++ bs).reverse = bs.reverse ++ as.reverse := by
+  cases as
+  cases bs
+  simp
+
+@[simp] theorem reverse_eq_append_iff {xs ys zs : Array α} :
+    xs.reverse = ys ++ zs ↔ xs = zs.reverse ++ ys.reverse := by
+  cases xs
+  cases ys
+  cases zs
+  simp
+
+/-- Reversing a flatten is the same as reversing the order of parts and reversing all parts. -/
+theorem reverse_flatten (L : Array (Array α)) :
+    L.flatten.reverse = (L.map reverse).reverse.flatten := by
+  cases L using array₂_induction
+  simp [flatten_toArray, List.reverse_flatten, Function.comp_def]
+
+/-- Flattening a reverse is the same as reversing all parts and reversing the flattened result. -/
+theorem flatten_reverse (L : Array (Array α)) :
+    L.reverse.flatten = (L.map reverse).flatten.reverse := by
+  cases L using array₂_induction
+  simp [flatten_toArray, List.flatten_reverse, Function.comp_def]
+
+theorem reverse_flatMap {β} (l : Array α) (f : α → Array β) :
+    (l.flatMap f).reverse = l.reverse.flatMap (reverse ∘ f) := by
+  cases l
+  simp [List.reverse_flatMap, Function.comp_def]
+
+theorem flatMap_reverse {β} (l : Array α) (f : α → Array β) :
+    (l.reverse.flatMap f) = (l.flatMap (reverse ∘ f)).reverse := by
+  cases l
+  simp [List.flatMap_reverse, Function.comp_def]
+
+@[simp] theorem reverse_mkArray (n) (a : α) : reverse (mkArray n a) = mkArray n a := by
+  rw [← toList_inj]
+  simp
+
 /-! Content below this point has not yet been aligned with `List`. -/
 
+/-! ### sum -/
+
+theorem sum_eq_sum_toList [Add α] [Zero α] (as : Array α) : as.toList.sum = as.sum := by
+  cases as
+  simp [Array.sum, List.sum]
+
 -- This is a duplicate of `List.toArray_toList`.
 -- It's confusing to guess which namespace this theorem should live in,
 -- so we provide both.
@@ -2320,6 +2628,7 @@ theorem getElem?_push_eq (a : Array α) (x : α) : (a.push x)[a.size]? = some x
 
 @[deprecated getElem?_size (since := "2024-10-21")] abbrev get?_size := @getElem?_size
 
+@[deprecated getElem_set_self (since := "2025-01-17")]
 theorem get_set_eq (a : Array α) (i : Nat) (v : α) (h : i < a.size) :
     (a.set i v h)[i]'(by simp [h]) = v := by
   simp only [set, ← getElem_toList, List.getElem_set_self]
@@ -2343,17 +2652,9 @@ theorem get_set (a : Array α) (i : Nat) (hi : i < a.size) (j : Nat) (hj : j < a
     (h : i ≠ j) : (a.set i v)[j]'(by simp [*]) = a[j] := by
   simp only [set, ← getElem_toList, List.getElem_set_ne h]
 
-theorem swap_def (a : Array α) (i j : Nat) (hi hj) :
-    a.swap i j hi hj = (a.set i a[j]).set j a[i] (by simpa using hj) := by
-  simp [swap]
-
 @[simp] theorem toList_swap (a : Array α) (i j : Nat) (hi hj) :
     (a.swap i j hi hj).toList = (a.toList.set i a[j]).set j a[i] := by simp [swap_def]
 
-theorem getElem?_swap (a : Array α) (i j : Nat) (hi hj) (k : Nat) : (a.swap i j hi hj)[k]? =
-    if j = k then some a[i] else if i = k then some a[j] else a[k]? := by
-  simp [swap_def, get?_set]
-
 @[simp] theorem swapAt_def (a : Array α) (i : Nat) (v : α) (hi) :
     a.swapAt i v hi = (a[i], a.set i v) := rfl
 
@@ -2407,15 +2708,6 @@ theorem size_eq_length_toList (as : Array α) : as.size = as.toList.length := rf
 
 @[deprecated size_swapIfInBounds (since := "2024-11-24")] abbrev size_swap! := @size_swapIfInBounds
 
-@[simp] theorem size_reverse (a : Array α) : a.reverse.size = a.size := by
-  let rec go (as : Array α) (i j) : (reverse.loop as i j).size = as.size := by
-    rw [reverse.loop]
-    if h : i < j then
-      simp [(go · (i+1) ⟨j-1, ·⟩), h]
-    else simp [h]
-    termination_by j - i
-  simp only [reverse]; split <;> simp [go]
-
 @[simp] theorem size_range {n : Nat} : (range n).size = n := by
   induction n <;> simp [range]
 
@@ -2426,61 +2718,6 @@ theorem size_eq_length_toList (as : Array α) : as.size = as.toList.length := rf
 theorem getElem_range {n : Nat} {x : Nat} (h : x < (Array.range n).size) : (Array.range n)[x] = x := by
   simp [← getElem_toList]
 
-@[simp] theorem toList_reverse (a : Array α) : a.reverse.toList = a.toList.reverse := by
-  let rec go (as : Array α) (i j hj)
-      (h : i + j + 1 = a.size) (h₂ : as.size = a.size)
-      (H : ∀ k, as.toList[k]? = if i ≤ k ∧ k ≤ j then a.toList[k]? else a.toList.reverse[k]?)
-      (k : Nat) : (reverse.loop as i ⟨j, hj⟩).toList[k]? = a.toList.reverse[k]? := by
-    rw [reverse.loop]; dsimp only; split <;> rename_i h₁
-    · match j with | j+1 => ?_
-      simp only [Nat.add_sub_cancel]
-      rw [(go · (i+1) j)]
-      · rwa [Nat.add_right_comm i]
-      · simp [size_swap, h₂]
-      · intro k
-        rw [getElem?_toList, getElem?_swap]
-        simp only [H, ← getElem_toList, ← List.getElem?_eq_getElem, Nat.le_of_lt h₁,
-          ← getElem?_toList]
-        split <;> rename_i h₂
-        · simp only [← h₂, Nat.not_le.2 (Nat.lt_succ_self _), Nat.le_refl, and_false]
-          exact (List.getElem?_reverse' (j+1) i (Eq.trans (by simp_arith) h)).symm
-        split <;> rename_i h₃
-        · simp only [← h₃, Nat.not_le.2 (Nat.lt_succ_self _), Nat.le_refl, false_and]
-          exact (List.getElem?_reverse' i (j+1) (Eq.trans (by simp_arith) h)).symm
-        simp only [Nat.succ_le, Nat.lt_iff_le_and_ne.trans (and_iff_left h₃),
-          Nat.lt_succ.symm.trans (Nat.lt_iff_le_and_ne.trans (and_iff_left (Ne.symm h₂)))]
-    · rw [H]; split <;> rename_i h₂
-      · cases Nat.le_antisymm (Nat.not_lt.1 h₁) (Nat.le_trans h₂.1 h₂.2)
-        cases Nat.le_antisymm h₂.1 h₂.2
-        exact (List.getElem?_reverse' _ _ h).symm
-      · rfl
-    termination_by j - i
-  simp only [reverse]
-  split
-  · match a with | ⟨[]⟩ | ⟨[_]⟩ => rfl
-  · have := Nat.sub_add_cancel (Nat.le_of_not_le ‹_›)
-    refine List.ext_getElem? <| go _ _ _ _ (by simp [this]) rfl fun k => ?_
-    split
-    · rfl
-    · rename_i h
-      simp only [← show k < _ + 1 ↔ _ from Nat.lt_succ (n := a.size - 1), this, Nat.zero_le,
-        true_and, Nat.not_lt] at h
-      rw [List.getElem?_eq_none_iff.2 ‹_›, List.getElem?_eq_none_iff.2 (a.toList.length_reverse ▸ ‹_›)]
-
-end Array
-
-open Array
-
-namespace List
-
-@[simp] theorem reverse_toArray (l : List α) : l.toArray.reverse = l.reverse.toArray := by
-  apply ext'
-  simp only [toList_reverse]
-
-end List
-
-namespace Array
-
 /-! ### foldlM and foldrM -/
 
 theorem foldlM_append [Monad m] [LawfulMonad m] (f : β → α → m β) (b) (l l' : Array α) :
@@ -3176,59 +3413,6 @@ theorem foldr_map' (g : α → β) (f : α → α → α) (f' : β → β → β
   | nil => simp
   | cons xs xss ih => simp [ih]
 
-/-! ### sum -/
-
-theorem sum_eq_sum_toList [Add α] [Zero α] (as : Array α) : as.sum = as.toList.sum := by
-  cases as
-  simp [Array.sum, List.sum]
-
-/-! ### mkArray -/
-
-theorem eq_mkArray_of_mem {a : α} {l : Array α} (h : ∀ (b) (_ : b ∈ l), b = a) : l = mkArray l.size a := by
-  rcases l with ⟨l⟩
-  have := List.eq_replicate_of_mem (by simpa using h)
-  rw [this]
-  simp
-
-theorem eq_mkArray_iff {a : α} {n} {l : Array α} :
-    l = mkArray n a ↔ l.size = n ∧ ∀ (b) (_ : b ∈ l), b = a := by
-  rcases l with ⟨l⟩
-  simp [← List.eq_replicate_iff, toArray_eq]
-
-theorem map_eq_mkArray_iff {l : Array α} {f : α → β} {b : β} :
-    l.map f = mkArray l.size b ↔ ∀ x ∈ l, f x = b := by
-  simp [eq_mkArray_iff]
-
-@[simp] theorem mem_mkArray (a : α) (n : Nat) : b ∈ mkArray n a ↔ n ≠ 0 ∧ b = a := by
-  rw [mkArray, mem_toArray]
-  simp
-
-@[simp] theorem map_const (l : Array α) (b : β) : map (Function.const α b) l = mkArray l.size b :=
-  map_eq_mkArray_iff.mpr fun _ _ => rfl
-
-@[simp] theorem map_const_fun (x : β) : map (Function.const α x) = (mkArray ·.size x) := by
-  funext l
-  simp
-
-/-- Variant of `map_const` using a lambda rather than `Function.const`. -/
--- This can not be a `@[simp]` lemma because it would fire on every `Array.map`.
-theorem map_const' (l : Array α) (b : β) : map (fun _ => b) l = mkArray l.size b :=
-  map_const l b
-
-@[simp] theorem sum_mkArray_nat (n : Nat) (a : Nat) : (mkArray n a).sum = n * a := by
-  simp [sum_eq_sum_toList, List.sum_replicate_nat]
-
-/-! ### reverse -/
-
-@[simp] theorem mem_reverse {x : α} {as : Array α} : x ∈ as.reverse ↔ x ∈ as := by
-  cases as
-  simp
-
-@[simp] theorem getElem_reverse (as : Array α) (i : Nat) (hi : i < as.reverse.size) :
-    (as.reverse)[i] = as[as.size - 1 - i]'(by simp at hi; omega) := by
-  cases as
-  simp [Array.getElem_reverse]
-
 /-! ### findSomeRevM?, findRevM?, findSomeRev?, findRev? -/
 
 @[simp] theorem findSomeRevM?_eq_findSomeM?_reverse

src/Init/Data/Array/MapIdx.lean

@@ -12,81 +12,82 @@ namespace Array
 /-! ### mapFinIdx -/
 
 -- This could also be proved from `SatisfiesM_mapIdxM` in Batteries.
-theorem mapFinIdx_induction (as : Array α) (f : Fin as.size → α → β)
+theorem mapFinIdx_induction (as : Array α) (f : (i : Nat) → α → (h : i < as.size) → β)
     (motive : Nat → Prop) (h0 : motive 0)
-    (p : Fin as.size → β → Prop)
-    (hs : ∀ i, motive i.1 → p i (f i as[i]) ∧ motive (i + 1)) :
+    (p : (i : Nat) → β → (h : i < as.size) → Prop)
+    (hs : ∀ i h, motive i → p i (f i as[i] h) h ∧ motive (i + 1)) :
     motive as.size ∧ ∃ eq : (Array.mapFinIdx as f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((Array.mapFinIdx as f)[i]) := by
-  let rec go {bs i j h} (h₁ : j = bs.size) (h₂ : ∀ i h h', p ⟨i, h⟩ bs[i]) (hm : motive j) :
+      ∀ i h, p i ((Array.mapFinIdx as f)[i]) h := by
+  let rec go {bs i j h} (h₁ : j = bs.size) (h₂ : ∀ i h h', p i bs[i] h) (hm : motive j) :
     let arr : Array β := Array.mapFinIdxM.map (m := Id) as f i j h bs
-    motive as.size ∧ ∃ eq : arr.size = as.size, ∀ i h, p ⟨i, h⟩ arr[i] := by
+    motive as.size ∧ ∃ eq : arr.size = as.size, ∀ i h, p i arr[i] h := by
     induction i generalizing j bs with simp [mapFinIdxM.map]
     | zero =>
       have := (Nat.zero_add _).symm.trans h
       exact ⟨this ▸ hm, h₁ ▸ this, fun _ _ => h₂ ..⟩
     | succ i ih =>
-      apply @ih (bs.push (f ⟨j, by omega⟩ as[j])) (j + 1) (by omega) (by simp; omega)
+      apply @ih (bs.push (f j as[j] (by omega))) (j + 1) (by omega) (by simp; omega)
       · intro i i_lt h'
         rw [getElem_push]
         split
         · apply h₂
         · simp only [size_push] at h'
           obtain rfl : i = j := by omega
-          apply (hs ⟨i, by omega⟩ hm).1
-      · exact (hs ⟨j, by omega⟩ hm).2
+          apply (hs i (by omega) hm).1
+      · exact (hs j (by omega) hm).2
   simp [mapFinIdx, mapFinIdxM]; exact go rfl nofun h0
 
-theorem mapFinIdx_spec (as : Array α) (f : Fin as.size → α → β)
-    (p : Fin as.size → β → Prop) (hs : ∀ i, p i (f i as[i])) :
+theorem mapFinIdx_spec (as : Array α) (f : (i : Nat) → α → (h : i < as.size) → β)
+    (p : (i : Nat) → β → (h : i < as.size) → Prop) (hs : ∀ i h, p i (f i as[i] h) h) :
     ∃ eq : (Array.mapFinIdx as f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((Array.mapFinIdx as f)[i]) :=
-  (mapFinIdx_induction _ _ (fun _ => True) trivial p fun _ _ => ⟨hs .., trivial⟩).2
+      ∀ i h, p i ((Array.mapFinIdx as f)[i]) h :=
+  (mapFinIdx_induction _ _ (fun _ => True) trivial p fun _ _ _ => ⟨hs .., trivial⟩).2
 
-@[simp] theorem size_mapFinIdx (a : Array α) (f : Fin a.size → α → β) : (a.mapFinIdx f).size = a.size :=
-  (mapFinIdx_spec (p := fun _ _ => True) (hs := fun _ => trivial)).1
+@[simp] theorem size_mapFinIdx (a : Array α) (f : (i : Nat) → α → (h : i < a.size) → β) :
+    (a.mapFinIdx f).size = a.size :=
+  (mapFinIdx_spec (p := fun _ _ _ => True) (hs := fun _ _ => trivial)).1
 
 @[simp] theorem size_zipWithIndex (as : Array α) : as.zipWithIndex.size = as.size :=
   Array.size_mapFinIdx _ _
 
-@[simp] theorem getElem_mapFinIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat)
+@[simp] theorem getElem_mapFinIdx (a : Array α) (f : (i : Nat) → α → (h : i < a.size) → β) (i : Nat)
     (h : i < (mapFinIdx a f).size) :
-    (a.mapFinIdx f)[i] = f ⟨i, by simp_all⟩ (a[i]'(by simp_all)) :=
-  (mapFinIdx_spec _ _ (fun i b => b = f i a[i]) fun _ => rfl).2 i _
+    (a.mapFinIdx f)[i] = f i (a[i]'(by simp_all))  (by simp_all) :=
+  (mapFinIdx_spec _ _ (fun i b h => b = f i a[i] h) fun _ _ => rfl).2 i _
 
-@[simp] theorem getElem?_mapFinIdx (a : Array α) (f : Fin a.size → α → β) (i : Nat) :
+@[simp] theorem getElem?_mapFinIdx (a : Array α) (f : (i : Nat) → α → (h : i < a.size) → β) (i : Nat) :
     (a.mapFinIdx f)[i]? =
-      a[i]?.pbind fun b h => f ⟨i, (getElem?_eq_some_iff.1 h).1⟩ b := by
+      a[i]?.pbind fun b h => f i b (getElem?_eq_some_iff.1 h).1 := by
   simp only [getElem?_def, size_mapFinIdx, getElem_mapFinIdx]
   split <;> simp_all
 
-@[simp] theorem toList_mapFinIdx (a : Array α) (f : Fin a.size → α → β) :
-    (a.mapFinIdx f).toList = a.toList.mapFinIdx (fun i a => f ⟨i, by simp⟩ a) := by
+@[simp] theorem toList_mapFinIdx (a : Array α) (f : (i : Nat) → α → (h : i < a.size) → β) :
+    (a.mapFinIdx f).toList = a.toList.mapFinIdx (fun i a h => f i a (by simpa)) := by
   apply List.ext_getElem <;> simp
 
 /-! ### mapIdx -/
 
 theorem mapIdx_induction (f : Nat → α → β) (as : Array α)
     (motive : Nat → Prop) (h0 : motive 0)
-    (p : Fin as.size → β → Prop)
-    (hs : ∀ i, motive i.1 → p i (f i as[i]) ∧ motive (i + 1)) :
+    (p : (i : Nat) → β → (h : i < as.size) → Prop)
+    (hs : ∀ i h, motive i → p i (f i as[i]) h ∧ motive (i + 1)) :
     motive as.size ∧ ∃ eq : (as.mapIdx f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((as.mapIdx f)[i]) :=
-  mapFinIdx_induction as (fun i a => f i a) motive h0 p hs
+      ∀ i h, p i ((as.mapIdx f)[i]) h :=
+  mapFinIdx_induction as (fun i a _ => f i a) motive h0 p hs
 
 theorem mapIdx_spec (f : Nat → α → β) (as : Array α)
-    (p : Fin as.size → β → Prop) (hs : ∀ i, p i (f i as[i])) :
+    (p : (i : Nat) → β → (h : i < as.size) → Prop) (hs : ∀ i h, p i (f i as[i]) h) :
     ∃ eq : (as.mapIdx f).size = as.size,
-      ∀ i h, p ⟨i, h⟩ ((as.mapIdx f)[i]) :=
-  (mapIdx_induction _ _ (fun _ => True) trivial p fun _ _ => ⟨hs .., trivial⟩).2
+      ∀ i h, p i ((as.mapIdx f)[i]) h :=
+  (mapIdx_induction _ _ (fun _ => True) trivial p fun _ _ _ => ⟨hs .., trivial⟩).2
 
 @[simp] theorem size_mapIdx (f : Nat → α → β) (as : Array α) : (as.mapIdx f).size = as.size :=
-  (mapIdx_spec (p := fun _ _ => True) (hs := fun _ => trivial)).1
+  (mapIdx_spec (p := fun _ _ _ => True) (hs := fun _ _ => trivial)).1
 
 @[simp] theorem getElem_mapIdx (f : Nat → α → β) (as : Array α) (i : Nat)
     (h : i < (as.mapIdx f).size) :
     (as.mapIdx f)[i] = f i (as[i]'(by simp_all)) :=
-  (mapIdx_spec _ _ (fun i b => b = f i as[i]) fun _ => rfl).2 i (by simp_all)
+  (mapIdx_spec _ _ (fun i b h => b = f i as[i]) fun _ _ => rfl).2 i (by simp_all)
 
 @[simp] theorem getElem?_mapIdx (f : Nat → α → β) (as : Array α) (i : Nat) :
     (as.mapIdx f)[i]? =
@@ -101,7 +102,7 @@ end Array
 
 namespace List
 
-@[simp] theorem mapFinIdx_toArray (l : List α) (f : Fin l.length → α → β) :
+@[simp] theorem mapFinIdx_toArray (l : List α) (f : (i : Nat) → α → (h : i < l.length) → β) :
     l.toArray.mapFinIdx f = (l.mapFinIdx f).toArray := by
   ext <;> simp
 

src/Init/Data/BitVec/Lemmas.lean

@@ -1294,11 +1294,6 @@ theorem allOnes_shiftLeft_or_shiftLeft {x : BitVec w} {n : Nat} :
     BitVec.allOnes w <<< n ||| x <<< n = BitVec.allOnes w <<< n := by
   simp [← shiftLeft_or_distrib]
 
-@[deprecated shiftLeft_add (since := "2024-06-02")]
-theorem shiftLeft_shiftLeft {w : Nat} (x : BitVec w) (n m : Nat) :
-    (x <<< n) <<< m = x <<< (n + m) := by
-  rw [shiftLeft_add]
-
 /-! ### shiftLeft reductions from BitVec to Nat -/
 
 @[simp]
@@ -1946,11 +1941,6 @@ theorem msb_shiftLeft {x : BitVec w} {n : Nat} :
     (x <<< n).msb = x.getMsbD n := by
   simp [BitVec.msb]
 
-@[deprecated shiftRight_add (since := "2024-06-02")]
-theorem shiftRight_shiftRight {w : Nat} (x : BitVec w) (n m : Nat) :
-    (x >>> n) >>> m = x >>> (n + m) := by
-  rw [shiftRight_add]
-
 /-! ### rev -/
 
 theorem getLsbD_rev (x : BitVec w) (i : Fin w) :

src/Init/Data/Char/Lemmas.lean

@@ -70,5 +70,3 @@ theorem utf8Size_eq (c : Char) : c.utf8Size = 1 ∨ c.utf8Size = 2 ∨ c.utf8Siz
   rfl
 
 end Char
-
-@[deprecated Char.utf8Size (since := "2024-06-04")] abbrev String.csize := Char.utf8Size

src/Init/Data/List/Basic.lean

@@ -258,9 +258,6 @@ theorem ext_get? : ∀ {l₁ l₂ : List α}, (∀ n, l₁.get? n = l₂.get? n)
     have h0 : some a = some a' := h 0
     injection h0 with aa; simp only [aa, ext_get? fun n => h (n+1)]
 
-/-- Deprecated alias for `ext_get?`. The preferred extensionality theorem is now `ext_getElem?`. -/
-@[deprecated ext_get? (since := "2024-06-07")] abbrev ext := @ext_get?
-
 /-! ### getD -/
 
 /--
@@ -619,11 +616,6 @@ set_option linter.missingDocs false in
 set_option linter.missingDocs false in
 @[deprecated flatMap_cons (since := "2024-10-16")] abbrev cons_flatMap := @flatMap_cons
 
-set_option linter.missingDocs false in
-@[deprecated flatMap_nil (since := "2024-06-15")] abbrev nil_bind := @flatMap_nil
-set_option linter.missingDocs false in
-@[deprecated flatMap_cons (since := "2024-06-15")] abbrev cons_bind := @flatMap_cons
-
 /-! ### replicate -/
 
 /--
@@ -713,11 +705,6 @@ def elem [BEq α] (a : α) : List α → Bool
 theorem elem_cons [BEq α] {a : α} :
     (b::bs).elem a = match a == b with | true => true | false => bs.elem a := rfl
 
-/-- `notElem a l` is `!(elem a l)`. -/
-@[deprecated "Use `!(elem a l)` instead."(since := "2024-06-15")]
-def notElem [BEq α] (a : α) (as : List α) : Bool :=
-  !(as.elem a)
-
 /-! ### contains -/
 
 @[inherit_doc elem] abbrev contains [BEq α] (as : List α) (a : α) : Bool :=

src/Init/Data/List/Lemmas.lean

@@ -813,11 +813,6 @@ theorem getElem_cons_length (x : α) (xs : List α) (i : Nat) (h : i = xs.length
     (x :: xs)[i]'(by simp [h]) = (x :: xs).getLast (cons_ne_nil x xs) := by
   rw [getLast_eq_getElem]; cases h; rfl
 
-@[deprecated getElem_cons_length (since := "2024-06-12")]
-theorem get_cons_length (x : α) (xs : List α) (n : Nat) (h : n = xs.length) :
-    (x :: xs).get ⟨n, by simp [h]⟩ = (x :: xs).getLast (cons_ne_nil x xs) := by
-  simp [getElem_cons_length, h]
-
 /-! ### getLast? -/
 
 @[simp] theorem getLast?_singleton (a : α) : getLast? [a] = a := rfl
@@ -1026,21 +1021,10 @@ theorem getLast?_tail (l : List α) : (tail l).getLast? = if l.length = 1 then n
   | _ :: _, 0 => by simp
   | _ :: l, i+1 => by simp [getElem?_map f l i]
 
-@[deprecated getElem?_map (since := "2024-06-12")]
-theorem get?_map (f : α → β) : ∀ l i, (map f l).get? i = (l.get? i).map f
-  | [], _ => rfl
-  | _ :: _, 0 => rfl
-  | _ :: l, i+1 => get?_map f l i
-
 @[simp] theorem getElem_map (f : α → β) {l} {i : Nat} {h : i < (map f l).length} :
     (map f l)[i] = f (l[i]'(length_map l f ▸ h)) :=
   Option.some.inj <| by rw [← getElem?_eq_getElem, getElem?_map, getElem?_eq_getElem]; rfl
 
-@[deprecated getElem_map (since := "2024-06-12")]
-theorem get_map (f : α → β) {l i} :
-    get (map f l) i = f (get l ⟨i, length_map l f ▸ i.2⟩) := by
-  simp
-
 @[simp] theorem map_id_fun : map (id : α → α) = id := by
   funext l
   induction l <;> simp_all
@@ -1286,8 +1270,6 @@ theorem filter_map (f : β → α) (l : List β) : filter p (map f l) = map f (f
   | nil => rfl
   | cons a l IH => by_cases h : p (f a) <;> simp [*]
 
-@[deprecated filter_map (since := "2024-06-15")] abbrev map_filter := @filter_map
-
 theorem map_filter_eq_foldr (f : α → β) (p : α → Bool) (as : List α) :
     map f (filter p as) = foldr (fun a bs => bif p a then f a :: bs else bs) [] as := by
   induction as with
@@ -1332,8 +1314,6 @@ theorem filter_congr {p q : α → Bool} :
     · simp [pa, h.1 ▸ pa, filter_congr h.2]
     · simp [pa, h.1 ▸ pa, filter_congr h.2]
 
-@[deprecated filter_congr (since := "2024-06-20")] abbrev filter_congr' := @filter_congr
-
 theorem head_filter_of_pos {p : α → Bool} {l : List α} (w : l ≠ []) (h : p (l.head w)) :
     (filter p l).head ((ne_nil_of_mem (mem_filter.2 ⟨head_mem w, h⟩))) = l.head w := by
   cases l with
@@ -1561,11 +1541,6 @@ theorem getElem?_append {l₁ l₂ : List α} {i : Nat} :
   · exact getElem?_append_left h
   · exact getElem?_append_right (by simpa using h)
 
-@[deprecated getElem?_append_right (since := "2024-06-12")]
-theorem get?_append_right {l₁ l₂ : List α} {i : Nat} (h : l₁.length ≤ i) :
-    (l₁ ++ l₂).get? i = l₂.get? (i - l₁.length) := by
-  simp [getElem?_append_right, h]
-
 /-- Variant of `getElem_append_left` useful for rewriting from the small list to the big list. -/
 theorem getElem_append_left' (l₂ : List α) {l₁ : List α} {i : Nat} (hi : i < l₁.length) :
     l₁[i] = (l₁ ++ l₂)[i]'(by simpa using Nat.lt_add_right l₂.length hi) := by
@@ -1576,33 +1551,11 @@ theorem getElem_append_right' (l₁ : List α) {l₂ : List α} {i : Nat} (hi :
     l₂[i] = (l₁ ++ l₂)[i + l₁.length]'(by simpa [Nat.add_comm] using Nat.add_lt_add_left hi _) := by
   rw [getElem_append_right] <;> simp [*, le_add_left]
 
-@[deprecated "Deprecated without replacement." (since := "2024-06-12")]
-theorem get_append_right_aux {l₁ l₂ : List α} {i : Nat}
-  (h₁ : l₁.length ≤ i) (h₂ : i < (l₁ ++ l₂).length) : i - l₁.length < l₂.length := by
-  rw [length_append] at h₂
-  exact Nat.sub_lt_left_of_lt_add h₁ h₂
-
-set_option linter.deprecated false in
-@[deprecated getElem_append_right (since := "2024-06-12")]
-theorem get_append_right' {l₁ l₂ : List α} {i : Nat} (h₁ : l₁.length ≤ i) (h₂) :
-    (l₁ ++ l₂).get ⟨i, h₂⟩ = l₂.get ⟨i - l₁.length, get_append_right_aux h₁ h₂⟩ :=
-  Option.some.inj <| by rw [← get?_eq_get, ← get?_eq_get, get?_append_right h₁]
-
 theorem getElem_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) :
     l[i]'(eq ▸ h ▸ by simp_arith) = a := Option.some.inj <| by
   rw [← getElem?_eq_getElem, eq, getElem?_append_right (h ▸ Nat.le_refl _), h]
   simp
 
-@[deprecated "Deprecated without replacement." (since := "2024-06-12")]
-theorem get_of_append_proof {l : List α}
-    (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) : i < length l := eq ▸ h ▸ by simp_arith
-
-set_option linter.deprecated false in
-@[deprecated getElem_of_append (since := "2024-06-12")]
-theorem get_of_append {l : List α} (eq : l = l₁ ++ a :: l₂) (h : l₁.length = i) :
-    l.get ⟨i, get_of_append_proof eq h⟩ = a := Option.some.inj <| by
-  rw [← get?_eq_get, eq, get?_append_right (h ▸ Nat.le_refl _), h, Nat.sub_self]; rfl
-
 @[simp 1100] theorem singleton_append : [x] ++ l = x :: l := rfl
 
 theorem append_inj :
@@ -1653,26 +1606,6 @@ theorem getLast_concat {a : α} : ∀ (l : List α), getLast (l ++ [a]) (by simp
   | a::t => by
     simp [getLast_cons _, getLast_concat t]
 
-@[deprecated getElem_append (since := "2024-06-12")]
-theorem get_append {l₁ l₂ : List α} (n : Nat) (h : n < l₁.length) :
-    (l₁ ++ l₂).get ⟨n, length_append .. ▸ Nat.lt_add_right _ h⟩ = l₁.get ⟨n, h⟩ := by
-  simp [getElem_append, h]
-
-@[deprecated getElem_append_left (since := "2024-06-12")]
-theorem get_append_left (as bs : List α) (h : i < as.length) {h'} :
-    (as ++ bs).get ⟨i, h'⟩ = as.get ⟨i, h⟩ := by
-  simp [getElem_append_left, h, h']
-
-@[deprecated getElem_append_right (since := "2024-06-12")]
-theorem get_append_right (as bs : List α) (h : as.length ≤ i) {h' h''} :
-    (as ++ bs).get ⟨i, h'⟩ = bs.get ⟨i - as.length, h''⟩ := by
-  simp [getElem_append_right, h, h', h'']
-
-@[deprecated getElem?_append_left (since := "2024-06-12")]
-theorem get?_append {l₁ l₂ : List α} {n : Nat} (hn : n < l₁.length) :
-    (l₁ ++ l₂).get? n = l₁.get? n := by
-  simp [getElem?_append_left hn]
-
 @[simp] theorem append_eq_nil_iff : p ++ q = [] ↔ p = [] ∧ q = [] := by
   cases p <;> simp
 
@@ -2199,10 +2132,6 @@ theorem forall_mem_replicate {p : α → Prop} {a : α} {n} :
     (replicate n a)[m] = a :=
   eq_of_mem_replicate (getElem_mem _)
 
-@[deprecated getElem_replicate (since := "2024-06-12")]
-theorem get_replicate (a : α) {n : Nat} (m : Fin _) : (replicate n a).get m = a := by
-  simp
-
 theorem getElem?_replicate : (replicate n a)[m]? = if m < n then some a else none := by
   by_cases h : m < n
   · rw [getElem?_eq_getElem (by simpa), getElem_replicate, if_pos h]
@@ -2274,7 +2203,7 @@ theorem map_const' (l : List α) (b : β) : map (fun _ => b) l = replicate l.len
   · intro i h₁ h₂
     simp [getElem_set]
 
-@[simp] theorem append_replicate_replicate : replicate n a ++ replicate m a = replicate (n + m) a := by
+@[simp] theorem replicate_append_replicate : replicate n a ++ replicate m a = replicate (n + m) a := by
   rw [eq_replicate_iff]
   constructor
   · simp
@@ -2282,6 +2211,9 @@ theorem map_const' (l : List α) (b : β) : map (fun _ => b) l = replicate l.len
     simp only [mem_append, mem_replicate, ne_eq]
     rintro (⟨-, rfl⟩ | ⟨_, rfl⟩) <;> rfl
 
+@[deprecated replicate_append_replicate (since := "2025-01-16")]
+abbrev append_replicate_replicate := @replicate_append_replicate
+
 theorem append_eq_replicate_iff {l₁ l₂ : List α} {a : α} :
     l₁ ++ l₂ = replicate n a ↔
       l₁.length + l₂.length = n ∧ l₁ = replicate l₁.length a ∧ l₂ = replicate l₂.length a := by
@@ -2292,6 +2224,11 @@ theorem append_eq_replicate_iff {l₁ l₂ : List α} {a : α} :
 
 @[deprecated append_eq_replicate_iff (since := "2024-09-05")] abbrev append_eq_replicate := @append_eq_replicate_iff
 
+theorem replicate_eq_append_iff {l₁ l₂ : List α} {a : α} :
+    replicate n a = l₁ ++ l₂ ↔
+      l₁.length + l₂.length = n ∧ l₁ = replicate l₁.length a ∧ l₂ = replicate l₂.length a := by
+  rw [eq_comm, append_eq_replicate_iff]
+
 @[simp] theorem map_replicate : (replicate n a).map f = replicate n (f a) := by
   ext1 n
   simp only [getElem?_map, getElem?_replicate]
@@ -2343,7 +2280,7 @@ theorem filterMap_replicate_of_some {f : α → Option β} (h : f a = some b) :
   induction n with
   | zero => simp
   | succ n ih =>
-    simp only [replicate_succ, flatten_cons, ih, append_replicate_replicate, replicate_inj, or_true,
+    simp only [replicate_succ, flatten_cons, ih, replicate_append_replicate, replicate_inj, or_true,
       and_true, add_one_mul, Nat.add_comm]
 
 theorem flatMap_replicate {β} (f : α → List β) : (replicate n a).flatMap f = (replicate n (f a)).flatten := by
@@ -2430,10 +2367,6 @@ theorem getElem?_reverse' : ∀ {l : List α} (i j), i + j + 1 = length l →
     rw [getElem?_append_left, getElem?_reverse' _ _ this]
     rw [length_reverse, ← this]; apply Nat.lt_add_of_pos_right (Nat.succ_pos _)
 
-@[deprecated getElem?_reverse' (since := "2024-06-12")]
-theorem get?_reverse' {l : List α} (i j) (h : i + j + 1 = length l) : get? l.reverse i = get? l j := by
-  simp [getElem?_reverse' _ _ h]
-
 @[simp]
 theorem getElem?_reverse {l : List α} {i} (h : i < length l) :
     l.reverse[i]? = l[l.length - 1 - i]? :=
@@ -2448,11 +2381,6 @@ theorem getElem_reverse {l : List α} {i} (h : i < l.reverse.length) :
   rw [← getElem?_eq_getElem, ← getElem?_eq_getElem]
   rw [getElem?_reverse (by simpa using h)]
 
-@[deprecated getElem?_reverse (since := "2024-06-12")]
-theorem get?_reverse {l : List α} {i} (h : i < length l) :
-    get? l.reverse i = get? l (l.length - 1 - i) := by
-  simp [getElem?_reverse h]
-
 theorem reverseAux_reverseAux_nil (as bs : List α) : reverseAux (reverseAux as bs) [] = reverseAux bs as := by
   induction as generalizing bs with
   | nil => rfl
@@ -2493,10 +2421,6 @@ theorem mem_of_mem_getLast? {l : List α} {a : α} (h : a ∈ getLast? l) : a
 @[simp] theorem map_reverse (f : α → β) (l : List α) : l.reverse.map f = (l.map f).reverse := by
   induction l <;> simp [*]
 
-@[deprecated map_reverse (since := "2024-06-20")]
-theorem reverse_map (f : α → β) (l : List α) : (l.map f).reverse = l.reverse.map f := by
-  simp
-
 @[simp] theorem filter_reverse (p : α → Bool) (l : List α) : (l.reverse.filter p) = (l.filter p).reverse := by
   induction l with
   | nil => simp
@@ -2960,11 +2884,6 @@ are often used for theorems about `Array.pop`.
   | _::_::_, 0, _ => rfl
   | _::_::_, i+1, h => getElem_dropLast _ i (Nat.add_one_lt_add_one_iff.mp h)
 
-@[deprecated getElem_dropLast (since := "2024-06-12")]
-theorem get_dropLast (xs : List α) (i : Fin xs.dropLast.length) :
-    xs.dropLast.get i = xs.get ⟨i, Nat.lt_of_lt_of_le i.isLt (length_dropLast .. ▸ Nat.pred_le _)⟩ := by
-  simp
-
 theorem getElem?_dropLast (xs : List α) (i : Nat) :
     xs.dropLast[i]? = if i < xs.length - 1 then xs[i]? else none := by
   split
@@ -3502,29 +3421,6 @@ theorem mem_iff_get? {a} {l : List α} : a ∈ l ↔ ∃ n, l.get? n = some a :=
 
 /-! ### Deprecations -/
 
-@[deprecated getD_eq_getElem?_getD (since := "2024-06-12")]
-theorem getD_eq_get? : ∀ l n (a : α), getD l n a = (get? l n).getD a := by simp
-@[deprecated getElem_singleton (since := "2024-06-12")]
-theorem get_singleton (a : α) (n : Fin 1) : get [a] n = a := by simp
-@[deprecated getElem?_concat_length (since := "2024-06-12")]
-theorem get?_concat_length (l : List α) (a : α) : (l ++ [a]).get? l.length = some a := by simp
-@[deprecated getElem_set_self (since := "2024-06-12")]
-theorem get_set_eq {l : List α} {i : Nat} {a : α} (h : i < (l.set i a).length) :
-    (l.set i a).get ⟨i, h⟩ = a := by
-  simp
-@[deprecated getElem_set_ne (since := "2024-06-12")]
-theorem get_set_ne {l : List α} {i j : Nat} (h : i ≠ j) {a : α}
-    (hj : j < (l.set i a).length) :
-    (l.set i a).get ⟨j, hj⟩ = l.get ⟨j, by simp at hj; exact hj⟩ := by
-  simp [h]
-@[deprecated getElem_set (since := "2024-06-12")]
-theorem get_set {l : List α} {m n} {a : α} (h) :
-    (set l m a).get ⟨n, h⟩ = if m = n then a else l.get ⟨n, length_set .. ▸ h⟩ := by
-  simp [getElem_set]
-@[deprecated cons_inj_right (since := "2024-06-15")] abbrev cons_inj := @cons_inj_right
-@[deprecated ne_nil_of_length_eq_add_one (since := "2024-06-16")]
-abbrev ne_nil_of_length_eq_succ := @ne_nil_of_length_eq_add_one
-
 @[deprecated "Deprecated without replacement." (since := "2024-07-09")]
 theorem get_cons_cons_one : (a₁ :: a₂ :: as).get (1 : Fin (as.length + 2)) = a₂ := rfl
 

src/Init/Data/List/MapIdx.lean

@@ -22,13 +22,13 @@ namespace List
 Given a list `as = [a₀, a₁, ...]` function `f : Fin as.length → α → β`, returns the list
 `[f 0 a₀, f 1 a₁, ...]`.
 -/
-@[inline] def mapFinIdx (as : List α) (f : Fin as.length → α → β) : List β := go as #[] (by simp) where
+@[inline] def mapFinIdx (as : List α) (f : (i : Nat) → α → (h : i < as.length) → β) : List β := go as #[] (by simp) where
   /-- Auxiliary for `mapFinIdx`:
   `mapFinIdx.go [a₀, a₁, ...] acc = acc.toList ++ [f 0 a₀, f 1 a₁, ...]` -/
   @[specialize] go : (bs : List α) → (acc : Array β) → bs.length + acc.size = as.length → List β
   | [], acc, h => acc.toList
   | a :: as, acc, h =>
-    go as (acc.push (f ⟨acc.size, by simp at h; omega⟩ a)) (by simp at h ⊢; omega)
+    go as (acc.push (f acc.size a (by simp at h; omega))) (by simp at h ⊢; omega)
 
 /--
 Given a function `f : Nat → α → β` and `as : List α`, `as = [a₀, a₁, ...]`, returns the list
@@ -44,7 +44,7 @@ Given a function `f : Nat → α → β` and `as : List α`, `as = [a₀, a₁,
 /-! ### mapFinIdx -/
 
 @[simp]
-theorem mapFinIdx_nil {f : Fin 0 → α → β} : mapFinIdx [] f = [] :=
+theorem mapFinIdx_nil {f : (i : Nat) → α → (h : i < 0) → β} : mapFinIdx [] f = [] :=
   rfl
 
 @[simp] theorem length_mapFinIdx_go :
@@ -53,13 +53,16 @@ theorem mapFinIdx_nil {f : Fin 0 → α → β} : mapFinIdx [] f = [] :=
   | nil => simpa using h
   | cons _ _ ih => simp [mapFinIdx.go, ih]
 
-@[simp] theorem length_mapFinIdx {as : List α} {f : Fin as.length → α → β} :
+@[simp] theorem length_mapFinIdx {as : List α} {f : (i : Nat) → α → (h : i < as.length) → β} :
     (as.mapFinIdx f).length = as.length := by
   simp [mapFinIdx, length_mapFinIdx_go]
 
-theorem getElem_mapFinIdx_go {as : List α} {f : Fin as.length → α → β} {i : Nat} {h} {w} :
+theorem getElem_mapFinIdx_go {as : List α} {f : (i : Nat) → α → (h : i < as.length) → β} {i : Nat} {h} {w} :
     (mapFinIdx.go as f bs acc h)[i] =
-      if w' : i < acc.size then acc[i] else f ⟨i, by simp at w; omega⟩ (bs[i - acc.size]'(by simp at w; omega)) := by
+      if w' : i < acc.size then
+        acc[i]
+      else
+        f i (bs[i - acc.size]'(by simp at w; omega)) (by simp at w; omega) := by
   induction bs generalizing acc with
   | nil =>
     simp only [length_mapFinIdx_go, length_nil, Nat.zero_add] at w h
@@ -78,29 +81,30 @@ theorem getElem_mapFinIdx_go {as : List α} {f : Fin as.length → α → β} {i
     · have h₃ : i - acc.size = (i - (acc.size + 1)) + 1 := by omega
       simp [h₃]
 
-@[simp] theorem getElem_mapFinIdx {as : List α} {f : Fin as.length → α → β} {i : Nat} {h} :
-    (as.mapFinIdx f)[i] = f ⟨i, by simp at h; omega⟩ (as[i]'(by simp at h; omega)) := by
+@[simp] theorem getElem_mapFinIdx {as : List α} {f : (i : Nat) → α → (h : i < as.length) → β} {i : Nat} {h} :
+    (as.mapFinIdx f)[i] = f i (as[i]'(by simp at h; omega)) (by simp at h; omega) := by
   simp [mapFinIdx, getElem_mapFinIdx_go]
 
-theorem mapFinIdx_eq_ofFn {as : List α} {f : Fin as.length → α → β} :
-    as.mapFinIdx f = List.ofFn fun i : Fin as.length => f i as[i] := by
+theorem mapFinIdx_eq_ofFn {as : List α} {f : (i : Nat) → α → (h : i < as.length) → β} :
+    as.mapFinIdx f = List.ofFn fun i : Fin as.length => f i as[i] i.2 := by
   apply ext_getElem <;> simp
 
-@[simp] theorem getElem?_mapFinIdx {l : List α} {f : Fin l.length → α → β} {i : Nat} :
-    (l.mapFinIdx f)[i]? = l[i]?.pbind fun x m => f ⟨i, by simp [getElem?_eq_some_iff] at m; exact m.1⟩ x := by
+@[simp] theorem getElem?_mapFinIdx {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} {i : Nat} :
+    (l.mapFinIdx f)[i]? = l[i]?.pbind fun x m => f i x (by simp [getElem?_eq_some_iff] at m; exact m.1) := by
   simp only [getElem?_def, length_mapFinIdx, getElem_mapFinIdx]
   split <;> simp
 
 @[simp]
-theorem mapFinIdx_cons {l : List α} {a : α} {f : Fin (l.length + 1) → α → β} :
-    mapFinIdx (a :: l) f = f 0 a :: mapFinIdx l (fun i => f i.succ) := by
+theorem mapFinIdx_cons {l : List α} {a : α} {f : (i : Nat) → α → (h : i < l.length + 1) → β} :
+    mapFinIdx (a :: l) f = f 0 a (by omega) :: mapFinIdx l (fun i a h => f (i + 1) a (by omega)) := by
   apply ext_getElem
   · simp
   · rintro (_|i) h₁ h₂ <;> simp
 
-theorem mapFinIdx_append {K L : List α} {f : Fin (K ++ L).length → α → β} :
+theorem mapFinIdx_append {K L : List α} {f : (i : Nat) → α → (h : i < (K ++ L).length) → β} :
     (K ++ L).mapFinIdx f =
-      K.mapFinIdx (fun i => f (i.castLE (by simp))) ++ L.mapFinIdx (fun i => f ((i.natAdd K.length).cast (by simp))) := by
+      K.mapFinIdx (fun i a h => f i a (by simp; omega)) ++
+        L.mapFinIdx (fun i a h => f (i + K.length) a (by simp; omega)) := by
   apply ext_getElem
   · simp
   · intro i h₁ h₂
@@ -108,60 +112,57 @@ theorem mapFinIdx_append {K L : List α} {f : Fin (K ++ L).length → α → β}
     simp only [getElem_mapFinIdx, length_mapFinIdx]
     split <;> rename_i h
     · rw [getElem_append_left]
-      congr
     · simp only [Nat.not_lt] at h
       rw [getElem_append_right h]
       congr
-      simp
       omega
 
-@[simp] theorem mapFinIdx_concat {l : List α} {e : α} {f : Fin (l ++ [e]).length → α → β}:
-    (l ++ [e]).mapFinIdx f = l.mapFinIdx (fun i => f (i.castLE (by simp))) ++ [f ⟨l.length, by simp⟩ e] := by
+@[simp] theorem mapFinIdx_concat {l : List α} {e : α} {f : (i : Nat) → α → (h : i < (l ++ [e]).length) → β}:
+    (l ++ [e]).mapFinIdx f = l.mapFinIdx (fun i a h => f i a (by simp; omega)) ++ [f l.length e (by simp)] := by
   simp [mapFinIdx_append]
-  congr
 
-theorem mapFinIdx_singleton {a : α} {f : Fin 1 → α → β} :
-    [a].mapFinIdx f = [f ⟨0, by simp⟩ a] := by
+theorem mapFinIdx_singleton {a : α} {f : (i : Nat) → α → (h : i < 1) → β} :
+    [a].mapFinIdx f = [f 0 a (by simp)] := by
   simp
 
-theorem mapFinIdx_eq_enum_map {l : List α} {f : Fin l.length → α → β} :
+theorem mapFinIdx_eq_enum_map {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} :
     l.mapFinIdx f = l.enum.attach.map
       fun ⟨⟨i, x⟩, m⟩ =>
-        f ⟨i, by rw [mk_mem_enum_iff_getElem?, getElem?_eq_some_iff] at m; exact m.1⟩ x := by
+        f i x (by rw [mk_mem_enum_iff_getElem?, getElem?_eq_some_iff] at m; exact m.1) := by
   apply ext_getElem <;> simp
 
 @[simp]
-theorem mapFinIdx_eq_nil_iff {l : List α} {f : Fin l.length → α → β} :
+theorem mapFinIdx_eq_nil_iff {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} :
     l.mapFinIdx f = [] ↔ l = [] := by
   rw [mapFinIdx_eq_enum_map, map_eq_nil_iff, attach_eq_nil_iff, enum_eq_nil_iff]
 
-theorem mapFinIdx_ne_nil_iff {l : List α} {f : Fin l.length → α → β} :
+theorem mapFinIdx_ne_nil_iff {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} :
     l.mapFinIdx f ≠ [] ↔ l ≠ [] := by
   simp
 
-theorem exists_of_mem_mapFinIdx {b : β} {l : List α} {f : Fin l.length → α → β}
-    (h : b ∈ l.mapFinIdx f) : ∃ (i : Fin l.length), f i l[i] = b := by
+theorem exists_of_mem_mapFinIdx {b : β} {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β}
+    (h : b ∈ l.mapFinIdx f) : ∃ (i : Nat) (h : i < l.length), f i l[i] h = b := by
   rw [mapFinIdx_eq_enum_map] at h
   replace h := exists_of_mem_map h
   simp only [mem_attach, true_and, Subtype.exists, Prod.exists, mk_mem_enum_iff_getElem?] at h
   obtain ⟨i, b, h, rfl⟩ := h
   rw [getElem?_eq_some_iff] at h
   obtain ⟨h', rfl⟩ := h
-  exact ⟨⟨i, h'⟩, rfl⟩
+  exact ⟨i, h', rfl⟩
 
-@[simp] theorem mem_mapFinIdx {b : β} {l : List α} {f : Fin l.length → α → β} :
-    b ∈ l.mapFinIdx f ↔ ∃ (i : Fin l.length), f i l[i] = b := by
+@[simp] theorem mem_mapFinIdx {b : β} {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} :
+    b ∈ l.mapFinIdx f ↔ ∃ (i : Nat) (h : i < l.length), f i l[i] h = b := by
   constructor
   · intro h
     exact exists_of_mem_mapFinIdx h
   · rintro ⟨i, h, rfl⟩
     rw [mem_iff_getElem]
-    exact ⟨i, by simp⟩
+    exact ⟨i, by simpa using h, by simp⟩
 
-theorem mapFinIdx_eq_cons_iff {l : List α} {b : β} {f : Fin l.length → α → β} :
+theorem mapFinIdx_eq_cons_iff {l : List α} {b : β} {f : (i : Nat) → α → (h : i < l.length) → β} :
     l.mapFinIdx f = b :: l₂ ↔
-      ∃ (a : α) (l₁ : List α) (h : l = a :: l₁),
-        f ⟨0, by simp [h]⟩ a = b ∧ l₁.mapFinIdx (fun i => f (i.succ.cast (by simp [h]))) = l₂ := by
+      ∃ (a : α) (l₁ : List α) (w : l = a :: l₁),
+        f 0 a (by simp [w]) = b ∧ l₁.mapFinIdx (fun i a h => f (i + 1) a (by simp [w]; omega)) = l₂ := by
   cases l with
   | nil => simp
   | cons x l' =>
@@ -169,39 +170,48 @@ theorem mapFinIdx_eq_cons_iff {l : List α} {b : β} {f : Fin l.length → α
       exists_and_left]
     constructor
     · rintro ⟨rfl, rfl⟩
-      refine ⟨x, rfl, l', by simp⟩
-    · rintro ⟨a, ⟨rfl, h⟩, ⟨_, ⟨rfl, rfl⟩, h⟩⟩
-      exact ⟨rfl, h⟩
+      refine ⟨x, l', ⟨rfl, rfl⟩, by simp⟩
+    · rintro ⟨a, l', ⟨rfl, rfl⟩, ⟨rfl, rfl⟩⟩
+      exact ⟨rfl, by simp⟩
 
-theorem mapFinIdx_eq_cons_iff' {l : List α} {b : β} {f : Fin l.length → α → β} :
+theorem mapFinIdx_eq_cons_iff' {l : List α} {b : β} {f : (i : Nat) → α → (h : i < l.length) → β} :
     l.mapFinIdx f = b :: l₂ ↔
-      l.head?.pbind (fun x m => (f ⟨0, by cases l <;> simp_all⟩ x)) = some b ∧
-        l.tail?.attach.map (fun ⟨t, m⟩ => t.mapFinIdx fun i => f (i.succ.cast (by cases l <;> simp_all))) = some l₂ := by
+      l.head?.pbind (fun x m => (f 0 x (by cases l <;> simp_all))) = some b ∧
+        l.tail?.attach.map (fun ⟨t, m⟩ => t.mapFinIdx fun i a h => f (i + 1) a (by cases l <;> simp_all)) = some l₂ := by
   cases l <;> simp
 
-theorem mapFinIdx_eq_iff {l : List α} {f : Fin l.length → α → β} :
-    l.mapFinIdx f = l' ↔ ∃ h : l'.length = l.length, ∀ (i : Nat) (h : i < l.length), l'[i] = f ⟨i, h⟩ l[i] := by
+theorem mapFinIdx_eq_iff {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} :
+    l.mapFinIdx f = l' ↔ ∃ h : l'.length = l.length, ∀ (i : Nat) (h : i < l.length), l'[i] = f i l[i] h := by
   constructor
   · rintro rfl
     simp
   · rintro ⟨h, w⟩
     apply ext_getElem <;> simp_all
 
-theorem mapFinIdx_eq_mapFinIdx_iff {l : List α} {f g : Fin l.length → α → β} :
-    l.mapFinIdx f = l.mapFinIdx g ↔ ∀ (i : Fin l.length), f i l[i] = g i l[i] := by
+theorem mapFinIdx_eq_mapFinIdx_iff {l : List α} {f g : (i : Nat) → α → (h : i < l.length) → β} :
+    l.mapFinIdx f = l.mapFinIdx g ↔ ∀ (i : Nat) (h : i < l.length), f i l[i] h = g i l[i] h := by
   rw [eq_comm, mapFinIdx_eq_iff]
   simp [Fin.forall_iff]
 
-@[simp] theorem mapFinIdx_mapFinIdx {l : List α} {f : Fin l.length → α → β} {g : Fin _ → β → γ} :
-    (l.mapFinIdx f).mapFinIdx g = l.mapFinIdx (fun i => g (i.cast (by simp)) ∘ f i) := by
+@[simp] theorem mapFinIdx_mapFinIdx {l : List α}
+    {f : (i : Nat) → α → (h : i < l.length) → β}
+    {g : (i : Nat) → β → (h : i < (l.mapFinIdx f).length) → γ} :
+    (l.mapFinIdx f).mapFinIdx g = l.mapFinIdx (fun i a h => g i (f i a h) (by simpa)) := by
   simp [mapFinIdx_eq_iff]
 
-theorem mapFinIdx_eq_replicate_iff {l : List α} {f : Fin l.length → α → β} {b : β} :
-    l.mapFinIdx f = replicate l.length b ↔ ∀ (i : Fin l.length), f i l[i] = b := by
-  simp [eq_replicate_iff, length_mapFinIdx, mem_mapFinIdx, forall_exists_index, true_and]
+theorem mapFinIdx_eq_replicate_iff {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} {b : β} :
+    l.mapFinIdx f = replicate l.length b ↔ ∀ (i : Nat) (h : i < l.length), f i l[i] h = b := by
+  rw [eq_replicate_iff, length_mapFinIdx]
+  simp only [mem_mapFinIdx, forall_exists_index, true_and]
+  constructor
+  · intro w i h
+    exact w (f i l[i] h) i h rfl
+  · rintro w b i h rfl
+    exact w i h
 
-@[simp] theorem mapFinIdx_reverse {l : List α} {f : Fin l.reverse.length → α → β} :
-    l.reverse.mapFinIdx f = (l.mapFinIdx (fun i => f ⟨l.length - 1 - i, by simp; omega⟩)).reverse := by
+@[simp] theorem mapFinIdx_reverse {l : List α} {f : (i : Nat) → α → (h : i < l.reverse.length) → β} :
+    l.reverse.mapFinIdx f =
+      (l.mapFinIdx (fun i a h => f (l.length - 1 - i) a (by simp; omega))).reverse := by
   simp [mapFinIdx_eq_iff]
   intro i h
   congr
@@ -262,13 +272,13 @@ theorem getElem?_mapIdx_go : ∀ {l : List α} {arr : Array β} {i : Nat},
   rw [← getElem?_eq_getElem, getElem?_mapIdx, getElem?_eq_getElem (by simpa using h)]
   simp
 
-@[simp] theorem mapFinIdx_eq_mapIdx {l : List α} {f : Fin l.length → α → β} {g : Nat → α → β}
-    (h : ∀ (i : Fin l.length), f i l[i] = g i l[i]) :
+@[simp] theorem mapFinIdx_eq_mapIdx {l : List α} {f : (i : Nat) → α → (h : i < l.length) → β} {g : Nat → α → β}
+    (h : ∀ (i : Nat) (h : i < l.length), f i l[i] h = g i l[i]) :
     l.mapFinIdx f = l.mapIdx g := by
   simp_all [mapFinIdx_eq_iff]
 
 theorem mapIdx_eq_mapFinIdx {l : List α} {f : Nat → α → β} :
-    l.mapIdx f = l.mapFinIdx (fun i => f i) := by
+    l.mapIdx f = l.mapFinIdx (fun i a _ => f i a) := by
   simp [mapFinIdx_eq_mapIdx]
 
 theorem mapIdx_eq_enum_map {l : List α} :

src/Init/Data/List/Nat/TakeDrop.lean

@@ -47,41 +47,16 @@ length `> i`. Version designed to rewrite from the small list to the big list. -
     L[i]'(Nat.lt_of_lt_of_le h (length_take_le' _ _)) := by
   rw [length_take, Nat.lt_min] at h; rw [getElem_take' L _ h.1]
 
-/-- The `i`-th element of a list coincides with the `i`-th element of any of its prefixes of
-length `> i`. Version designed to rewrite from the big list to the small list. -/
-@[deprecated getElem_take' (since := "2024-06-12")]
-theorem get_take (L : List α) {i j : Nat} (hi : i < L.length) (hj : i < j) :
-    get L ⟨i, hi⟩ = get (L.take j) ⟨i, length_take .. ▸ Nat.lt_min.mpr ⟨hj, hi⟩⟩ := by
-  simp
-
-/-- The `i`-th element of a list coincides with the `i`-th element of any of its prefixes of
-length `> i`. Version designed to rewrite from the small list to the big list. -/
-@[deprecated getElem_take (since := "2024-06-12")]
-theorem get_take' (L : List α) {j i} :
-    get (L.take j) i =
-    get L ⟨i.1, Nat.lt_of_lt_of_le i.2 (length_take_le' _ _)⟩ := by
-  simp [getElem_take]
-
 theorem getElem?_take_eq_none {l : List α} {n m : Nat} (h : n ≤ m) :
     (l.take n)[m]? = none :=
   getElem?_eq_none <| Nat.le_trans (length_take_le _ _) h
 
-@[deprecated getElem?_take_eq_none (since := "2024-06-12")]
-theorem get?_take_eq_none {l : List α} {n m : Nat} (h : n ≤ m) :
-    (l.take n).get? m = none := by
-  simp [getElem?_take_eq_none h]
-
 theorem getElem?_take {l : List α} {n m : Nat} :
     (l.take n)[m]? = if m < n then l[m]? else none := by
   split
   · next h => exact getElem?_take_of_lt h
   · next h => exact getElem?_take_eq_none (Nat.le_of_not_lt h)
 
-@[deprecated getElem?_take (since := "2024-06-12")]
-theorem get?_take_eq_if {l : List α} {n m : Nat} :
-    (l.take n).get? m = if m < n then l.get? m else none := by
-  simp [getElem?_take]
-
 theorem head?_take {l : List α} {n : Nat} :
     (l.take n).head? = if n = 0 then none else l.head? := by
   simp [head?_eq_getElem?, getElem?_take]
@@ -226,13 +201,6 @@ theorem getElem_drop' (L : List α) {i j : Nat} (h : i + j < L.length) :
   · simp [Nat.min_eq_left this, Nat.add_sub_cancel_left]
   · simp [Nat.min_eq_left this, Nat.le_add_right]
 
-/-- The `i + j`-th element of a list coincides with the `j`-th element of the list obtained by
-dropping the first `i` elements. Version designed to rewrite from the big list to the small list. -/
-@[deprecated getElem_drop' (since := "2024-06-12")]
-theorem get_drop (L : List α) {i j : Nat} (h : i + j < L.length) :
-    get L ⟨i + j, h⟩ = get (L.drop i) ⟨j, lt_length_drop L h⟩ := by
-  simp [getElem_drop']
-
 /-- The `i + j`-th element of a list coincides with the `j`-th element of the list obtained by
 dropping the first `i` elements. Version designed to rewrite from the small list to the big list. -/
 @[simp] theorem getElem_drop (L : List α) {i : Nat} {j : Nat} {h : j < (L.drop i).length} :
@@ -241,15 +209,6 @@ dropping the first `i` elements. Version designed to rewrite from the small list
       exact Nat.add_lt_of_lt_sub (length_drop i L ▸ h)) := by
   rw [getElem_drop']
 
-/-- The `i + j`-th element of a list coincides with the `j`-th element of the list obtained by
-dropping the first `i` elements. Version designed to rewrite from the small list to the big list. -/
-@[deprecated getElem_drop' (since := "2024-06-12")]
-theorem get_drop' (L : List α) {i j} :
-    get (L.drop i) j = get L ⟨i + j, by
-      rw [Nat.add_comm]
-      exact Nat.add_lt_of_lt_sub (length_drop i L ▸ j.2)⟩ := by
-  simp
-
 @[simp]
 theorem getElem?_drop (L : List α) (i j : Nat) : (L.drop i)[j]? = L[i + j]? := by
   ext
@@ -261,10 +220,6 @@ theorem getElem?_drop (L : List α) (i j : Nat) : (L.drop i)[j]? = L[i + j]? :=
     rw [Nat.add_comm] at h
     apply Nat.lt_sub_of_add_lt h
 
-@[deprecated getElem?_drop (since := "2024-06-12")]
-theorem get?_drop (L : List α) (i j : Nat) : get? (L.drop i) j = get? L (i + j) := by
-  simp
-
 theorem mem_take_iff_getElem {l : List α} {a : α} :
     a ∈ l.take n ↔ ∃ (i : Nat) (hm : i < min n l.length), l[i] = a := by
   rw [mem_iff_getElem]

src/Init/Data/List/TakeDrop.lean

@@ -67,17 +67,9 @@ theorem getElem_cons_drop : ∀ (l : List α) (i : Nat) (h : i < l.length),
   | _::_, 0, _ => rfl
   | _::_, i+1, h => getElem_cons_drop _ i (Nat.add_one_lt_add_one_iff.mp h)
 
-@[deprecated getElem_cons_drop (since := "2024-06-12")]
-theorem get_cons_drop (l : List α) (i) : get l i :: drop (i + 1) l = drop i l := by
-  simp
-
 theorem drop_eq_getElem_cons {n} {l : List α} (h : n < l.length) : drop n l = l[n] :: drop (n + 1) l :=
   (getElem_cons_drop _ n h).symm
 
-@[deprecated drop_eq_getElem_cons (since := "2024-06-12")]
-theorem drop_eq_get_cons {n} {l : List α} (h) : drop n l = get l ⟨n, h⟩ :: drop (n + 1) l := by
-  simp [drop_eq_getElem_cons]
-
 @[simp]
 theorem getElem?_take_of_lt {l : List α} {n m : Nat} (h : m < n) : (l.take n)[m]? = l[m]? := by
   induction n generalizing l m with
@@ -91,10 +83,6 @@ theorem getElem?_take_of_lt {l : List α} {n m : Nat} (h : m < n) : (l.take n)[m
       · simp
       · simpa using hn (Nat.lt_of_succ_lt_succ h)
 
-@[deprecated getElem?_take_of_lt (since := "2024-06-12")]
-theorem get?_take {l : List α} {n m : Nat} (h : m < n) : (l.take n).get? m = l.get? m := by
-  simp [getElem?_take_of_lt, h]
-
 theorem getElem?_take_of_succ {l : List α} {n : Nat} : (l.take (n + 1))[n]? = l[n]? := by simp
 
 @[simp] theorem drop_drop (n : Nat) : ∀ (m) (l : List α), drop n (drop m l) = drop (m + n) l
@@ -111,10 +99,6 @@ theorem take_drop : ∀ (m n : Nat) (l : List α), take n (drop m l) = drop m (t
   | _, _, [] => by simp
   | _+1, _, _ :: _ => by simpa [Nat.succ_add, take_succ_cons, drop_succ_cons] using take_drop ..
 
-@[deprecated drop_drop (since := "2024-06-15")]
-theorem drop_add (m n) (l : List α) : drop (m + n) l = drop n (drop m l) := by
-  simp [drop_drop]
-
 @[simp]
 theorem tail_drop (l : List α) (n : Nat) : (l.drop n).tail = l.drop (n + 1) := by
   induction l generalizing n with

src/Init/Data/List/Zip.lean

@@ -76,15 +76,6 @@ theorem getElem?_zip_eq_some {l₁ : List α} {l₂ : List β} {z : α × β} {i
   · rintro ⟨h₀, h₁⟩
     exact ⟨_, _, h₀, h₁, rfl⟩
 
-@[deprecated getElem?_zipWith (since := "2024-06-12")]
-theorem get?_zipWith {f : α → β → γ} :
-    (List.zipWith f as bs).get? i = match as.get? i, bs.get? i with
-      | some a, some b => some (f a b) | _, _ => none := by
-  simp [getElem?_zipWith]
-
-set_option linter.deprecated false in
-@[deprecated getElem?_zipWith (since := "2024-06-07")] abbrev zipWith_get? := @get?_zipWith
-
 theorem head?_zipWith {f : α → β → γ} :
     (List.zipWith f as bs).head? = match as.head?, bs.head? with
       | some a, some b => some (f a b) | _, _ => none := by
@@ -369,15 +360,6 @@ theorem getElem?_zipWithAll {f : Option α → Option β → γ} {i : Nat} :
       cases i <;> simp_all
     | cons b bs => cases i <;> simp_all
 
-@[deprecated getElem?_zipWithAll (since := "2024-06-12")]
-theorem get?_zipWithAll {f : Option α → Option β → γ} :
-    (zipWithAll f as bs).get? i = match as.get? i, bs.get? i with
-      | none, none => .none | a?, b? => some (f a? b?) := by
-  simp [getElem?_zipWithAll]
-
-set_option linter.deprecated false in
-@[deprecated getElem?_zipWithAll (since := "2024-06-07")] abbrev zipWithAll_get? := @get?_zipWithAll
-
 theorem head?_zipWithAll {f : Option α → Option β → γ} :
     (zipWithAll f as bs).head? = match as.head?, bs.head? with
       | none, none => .none | a?, b? => some (f a? b?) := by

src/Init/Data/Nat/Basic.lean

@@ -788,9 +788,6 @@ theorem not_eq_zero_of_lt (h : b < a) : a ≠ 0 := by
 theorem pred_lt_of_lt {n m : Nat} (h : m < n) : pred n < n :=
   pred_lt (not_eq_zero_of_lt h)
 
-set_option linter.missingDocs false in
-@[deprecated pred_lt_of_lt (since := "2024-06-01")] abbrev pred_lt' := @pred_lt_of_lt
-
 theorem sub_one_lt_of_lt {n m : Nat} (h : m < n) : n - 1 < n :=
   sub_one_lt (not_eq_zero_of_lt h)
 
@@ -1074,9 +1071,6 @@ theorem pred_mul (n m : Nat) : pred n * m = n * m - m := by
   | zero   => simp
   | succ n => rw [Nat.pred_succ, succ_mul, Nat.add_sub_cancel]
 
-set_option linter.missingDocs false in
-@[deprecated pred_mul (since := "2024-06-01")] abbrev mul_pred_left := @pred_mul
-
 protected theorem sub_one_mul  (n m : Nat) : (n - 1) * m = n * m - m := by
   cases n with
   | zero   => simp
@@ -1086,9 +1080,6 @@ protected theorem sub_one_mul  (n m : Nat) : (n - 1) * m = n * m - m := by
 theorem mul_pred (n m : Nat) : n * pred m = n * m - n := by
   rw [Nat.mul_comm, pred_mul, Nat.mul_comm]
 
-set_option linter.missingDocs false in
-@[deprecated mul_pred (since := "2024-06-01")] abbrev mul_pred_right := @mul_pred
-
 theorem mul_sub_one (n m : Nat) : n * (m - 1) = n * m - n := by
   rw [Nat.mul_comm, Nat.sub_one_mul , Nat.mul_comm]
 

src/Init/Data/Nat/Bitwise/Lemmas.lean

@@ -711,6 +711,32 @@ theorem mul_add_lt_is_or {b : Nat} (b_lt : b < 2^i) (a : Nat) : 2^i * a + b = 2^
   rw [mod_two_eq_one_iff_testBit_zero, testBit_shiftLeft]
   simp
 
+theorem testBit_mul_two_pow (x i n : Nat) :
+    (x * 2 ^ n).testBit i = (decide (n ≤ i) && x.testBit (i - n)) := by
+  rw [← testBit_shiftLeft, shiftLeft_eq]
+
+theorem bitwise_mul_two_pow (of_false_false : f false false = false := by rfl) :
+    (bitwise f x y) * 2 ^ n = bitwise f (x * 2 ^ n) (y * 2 ^ n) := by
+  apply Nat.eq_of_testBit_eq
+  simp only [testBit_mul_two_pow, testBit_bitwise of_false_false, Bool.if_false_right]
+  intro i
+  by_cases hn : n ≤ i
+  · simp [hn]
+  · simp [hn, of_false_false]
+
+theorem shiftLeft_bitwise_distrib {a b : Nat} (of_false_false : f false false = false := by rfl) :
+    (bitwise f a b) <<< i = bitwise f (a <<< i) (b <<< i) := by
+  simp [shiftLeft_eq, bitwise_mul_two_pow of_false_false]
+
+theorem shiftLeft_and_distrib {a b : Nat} : (a &&& b) <<< i = a <<< i &&& b <<< i :=
+  shiftLeft_bitwise_distrib
+
+theorem shiftLeft_or_distrib {a b : Nat} : (a ||| b) <<< i = a <<< i ||| b <<< i :=
+  shiftLeft_bitwise_distrib
+
+theorem shiftLeft_xor_distrib {a b : Nat} : (a ^^^ b) <<< i = a <<< i ^^^ b <<< i :=
+  shiftLeft_bitwise_distrib
+
 @[simp] theorem decide_shiftRight_mod_two_eq_one :
     decide (x >>> i % 2 = 1) = x.testBit i := by
   simp only [testBit, one_and_eq_mod_two, mod_two_bne_zero]

src/Init/Data/Nat/Lemmas.lean

@@ -622,6 +622,14 @@ protected theorem pos_of_mul_pos_right {a b : Nat} (h : 0 < a * b) : 0 < a := by
     0 < a * b ↔ 0 < a :=
   ⟨Nat.pos_of_mul_pos_right, fun w => Nat.mul_pos w h⟩
 
+protected theorem pos_of_lt_mul_left {a b c : Nat} (h : a < b * c) : 0 < c := by
+  replace h : 0 < b * c := by omega
+  exact Nat.pos_of_mul_pos_left h
+
+protected theorem pos_of_lt_mul_right {a b c : Nat} (h : a < b * c) : 0 < b := by
+  replace h : 0 < b * c := by omega
+  exact Nat.pos_of_mul_pos_right h
+
 /-! ### div/mod -/
 
 theorem mod_two_eq_zero_or_one (n : Nat) : n % 2 = 0 ∨ n % 2 = 1 :=
@@ -995,11 +1003,6 @@ theorem shiftLeft_add (m n : Nat) : ∀ k, m <<< (n + k) = (m <<< n) <<< k
   | 0 => rfl
   | k + 1 => by simp [← Nat.add_assoc, shiftLeft_add _ _ k, shiftLeft_succ]
 
-@[deprecated shiftLeft_add (since := "2024-06-02")]
-theorem shiftLeft_shiftLeft (m n : Nat) : ∀ k, (m <<< n) <<< k = m <<< (n + k)
-  | 0 => rfl
-  | k + 1 => by simp [← Nat.add_assoc, shiftLeft_shiftLeft _ _ k, shiftLeft_succ]
-
 @[simp] theorem shiftLeft_shiftRight (x n : Nat) : x <<< n >>> n = x := by
   rw [Nat.shiftLeft_eq, Nat.shiftRight_eq_div_pow, Nat.mul_div_cancel _ (Nat.two_pow_pos _)]
 

src/Init/Data/UInt/Lemmas.lean

@@ -234,23 +234,3 @@ theorem UInt32.toNat_le_of_le {n : UInt32} {m : Nat} (h : m < size) : n ≤ ofNa
 
 theorem UInt32.le_toNat_of_le {n : UInt32} {m : Nat} (h : m < size) : ofNat m ≤ n → m ≤ n.toNat := by
   simp [le_def, BitVec.le_def, UInt32.toNat, toBitVec_eq_of_lt h]
-
-@[deprecated UInt8.toNat_zero (since := "2024-06-23")] protected abbrev UInt8.zero_toNat := @UInt8.toNat_zero
-@[deprecated UInt8.toNat_div (since := "2024-06-23")] protected abbrev UInt8.div_toNat := @UInt8.toNat_div
-@[deprecated UInt8.toNat_mod (since := "2024-06-23")] protected abbrev UInt8.mod_toNat := @UInt8.toNat_mod
-
-@[deprecated UInt16.toNat_zero (since := "2024-06-23")] protected abbrev UInt16.zero_toNat := @UInt16.toNat_zero
-@[deprecated UInt16.toNat_div (since := "2024-06-23")] protected abbrev UInt16.div_toNat := @UInt16.toNat_div
-@[deprecated UInt16.toNat_mod (since := "2024-06-23")] protected abbrev UInt16.mod_toNat := @UInt16.toNat_mod
-
-@[deprecated UInt32.toNat_zero (since := "2024-06-23")] protected abbrev UInt32.zero_toNat := @UInt32.toNat_zero
-@[deprecated UInt32.toNat_div (since := "2024-06-23")] protected abbrev UInt32.div_toNat := @UInt32.toNat_div
-@[deprecated UInt32.toNat_mod (since := "2024-06-23")] protected abbrev UInt32.mod_toNat := @UInt32.toNat_mod
-
-@[deprecated UInt64.toNat_zero (since := "2024-06-23")] protected abbrev UInt64.zero_toNat := @UInt64.toNat_zero
-@[deprecated UInt64.toNat_div (since := "2024-06-23")] protected abbrev UInt64.div_toNat := @UInt64.toNat_div
-@[deprecated UInt64.toNat_mod (since := "2024-06-23")] protected abbrev UInt64.mod_toNat := @UInt64.toNat_mod
-
-@[deprecated USize.toNat_zero (since := "2024-06-23")] protected abbrev USize.zero_toNat := @USize.toNat_zero
-@[deprecated USize.toNat_div (since := "2024-06-23")] protected abbrev USize.div_toNat := @USize.toNat_div
-@[deprecated USize.toNat_mod (since := "2024-06-23")] protected abbrev USize.mod_toNat := @USize.toNat_mod

src/Init/Data/Vector/Lemmas.lean

@@ -475,7 +475,7 @@ theorem singleton_inj : #v[a] = #v[b] ↔ a = b := by
 theorem mkVector_succ : mkVector (n + 1) a = (mkVector n a).push a := by
   simp [mkVector, Array.mkArray_succ]
 
-theorem mkVector_inj : mkVector n a = mkVector n b ↔ n = 0 ∨ a = b := by
+@[simp] theorem mkVector_inj : mkVector n a = mkVector n b ↔ n = 0 ∨ a = b := by
   simp [← toArray_inj, toArray_mkVector, Array.mkArray_inj]
 
 /-! ## L[i] and L[i]? -/
@@ -1456,6 +1456,44 @@ theorem append_eq_map_iff {f : α → β} :
       mk (L.map toArray).flatten (by simp [Function.comp_def, Array.map_const', h]) := by
   simp [flatten]
 
+@[simp] theorem getElem_flatten (l : Vector (Vector β m) n) (i : Nat) (hi : i < n * m) :
+    l.flatten[i] =
+      haveI : i / m < n := by rwa [Nat.div_lt_iff_lt_mul (Nat.pos_of_lt_mul_left hi)]
+      haveI : i % m < m := Nat.mod_lt _ (Nat.pos_of_lt_mul_left hi)
+      l[i / m][i % m] := by
+  rcases l with ⟨⟨l⟩, rfl⟩
+  simp only [flatten_mk, List.map_toArray, getElem_mk, List.getElem_toArray, Array.flatten_toArray]
+  induction l generalizing i with
+  | nil => simp at hi
+  | cons a l ih =>
+    simp only [List.map_cons, List.map_map, List.flatten_cons]
+    by_cases h : i < m
+    · rw [List.getElem_append_left (by simpa)]
+      have h₁ : i / m = 0 := Nat.div_eq_of_lt h
+      have h₂ : i % m = i := Nat.mod_eq_of_lt h
+      simp [h₁, h₂]
+    · have h₁ : a.toList.length ≤ i := by simp; omega
+      rw [List.getElem_append_right h₁]
+      simp only [Array.length_toList, size_toArray]
+      specialize ih (i - m) (by simp_all [Nat.add_one_mul]; omega)
+      have h₂ : i / m = (i - m) / m + 1 := by
+        conv => lhs; rw [show i = i - m + m by omega]
+        rw [Nat.add_div_right]
+        exact Nat.pos_of_lt_mul_left hi
+      simp only [Array.length_toList, size_toArray] at h₁
+      have h₃ : (i - m) % m = i % m := (Nat.mod_eq_sub_mod h₁).symm
+      simp_all
+
+theorem getElem?_flatten (l : Vector (Vector β m) n) (i : Nat) :
+    l.flatten[i]? =
+      if hi : i < n * m then
+        haveI : i / m < n := by rwa [Nat.div_lt_iff_lt_mul (Nat.pos_of_lt_mul_left hi)]
+        haveI : i % m < m := Nat.mod_lt _ (Nat.pos_of_lt_mul_left hi)
+        some l[i / m][i % m]
+      else
+        none := by
+  simp [getElem?_def]
+
 @[simp] theorem flatten_singleton (l : Vector α n) : #v[l].flatten = l.cast (by simp) := by
   simp [flatten]
 
@@ -1542,6 +1580,23 @@ theorem flatMap_def (l : Vector α n) (f : α → Vector β m) : l.flatMap f = f
   rcases l with ⟨l, rfl⟩
   simp [Array.flatMap_def, Function.comp_def]
 
+@[simp] theorem getElem_flatMap (l : Vector α n) (f : α → Vector β m) (i : Nat) (hi : i < n * m) :
+    (l.flatMap f)[i] =
+      haveI : i / m < n := by rwa [Nat.div_lt_iff_lt_mul (Nat.pos_of_lt_mul_left hi)]
+      haveI : i % m < m := Nat.mod_lt _ (Nat.pos_of_lt_mul_left hi)
+      (f (l[i / m]))[i % m] := by
+  rw [flatMap_def, getElem_flatten, getElem_map]
+
+theorem getElem?_flatMap (l : Vector α n) (f : α → Vector β m) (i : Nat) :
+    (l.flatMap f)[i]? =
+      if hi : i < n * m then
+        haveI : i / m < n := by rwa [Nat.div_lt_iff_lt_mul (Nat.pos_of_lt_mul_left hi)]
+        haveI : i % m < m := Nat.mod_lt _ (Nat.pos_of_lt_mul_left hi)
+        some ((f (l[i / m]))[i % m])
+      else
+        none := by
+  simp [getElem?_def]
+
 @[simp] theorem flatMap_id (l : Vector (Vector α m) n) : l.flatMap id = l.flatten := by simp [flatMap_def]
 
 @[simp] theorem flatMap_id' (l : Vector (Vector α m) n) : l.flatMap (fun a => a) = l.flatten := by simp [flatMap_def]
@@ -1594,6 +1649,189 @@ theorem map_eq_flatMap {α β} (f : α → β) (l : Vector α n) :
   rcases l with ⟨l, rfl⟩
   simp [Array.map_eq_flatMap]
 
+/-! ### mkVector -/
+
+@[simp] theorem mkVector_one : mkVector 1 a = #v[a] := rfl
+
+/-- Variant of `mkVector_succ` that prepends `a` at the beginning of the vector. -/
+theorem mkVector_succ' : mkVector (n + 1) a = (#v[a] ++ mkVector n a).cast (by omega) := by
+  rw [← toArray_inj]
+  simp [Array.mkArray_succ']
+
+@[simp] theorem mem_mkVector {a b : α} {n} : b ∈ mkVector n a ↔ n ≠ 0 ∧ b = a := by
+  unfold mkVector
+  simp
+
+theorem eq_of_mem_mkVector {a b : α} {n} (h : b ∈ mkVector n a) : b = a := (mem_mkVector.1 h).2
+
+theorem forall_mem_mkVector {p : α → Prop} {a : α} {n} :
+    (∀ b, b ∈ mkVector n a → p b) ↔ n = 0 ∨ p a := by
+  cases n <;> simp [mem_mkVector]
+
+@[simp] theorem getElem_mkVector (a : α) (n i : Nat) (h : i < n) : (mkVector n a)[i] = a := by
+  simp [mkVector]
+
+theorem getElem?_mkVector (a : α) (n i : Nat) : (mkVector n a)[i]? = if i < n then some a else none := by
+  simp [getElem?_def]
+
+@[simp] theorem getElem?_mkVector_of_lt {n : Nat} {m : Nat} (h : m < n) : (mkVector n a)[m]? = some a := by
+  simp [getElem?_mkVector, h]
+
+theorem eq_mkVector_of_mem {a : α} {l : Vector α n} (h : ∀ (b) (_ : b ∈ l), b = a) : l = mkVector n a := by
+  rw [← toArray_inj]
+  simpa using Array.eq_mkArray_of_mem (l := l.toArray) (by simpa using h)
+
+theorem eq_mkVector_iff {a : α} {n} {l : Vector α n} :
+    l = mkVector n a ↔ ∀ (b) (_ : b ∈ l), b = a := by
+  rw [← toArray_inj]
+  simpa using Array.eq_mkArray_iff (l := l.toArray) (n := n)
+
+theorem map_eq_mkVector_iff {l : Vector α n} {f : α → β} {b : β} :
+    l.map f = mkVector n b ↔ ∀ x ∈ l, f x = b := by
+  simp [eq_mkVector_iff]
+
+@[simp] theorem map_const (l : Vector α n) (b : β) : map (Function.const α b) l = mkVector n b :=
+  map_eq_mkVector_iff.mpr fun _ _ => rfl
+
+@[simp] theorem map_const_fun (x : β) : map (n := n) (Function.const α x) = fun _ => mkVector n x := by
+  funext l
+  simp
+
+/-- Variant of `map_const` using a lambda rather than `Function.const`. -/
+-- This can not be a `@[simp]` lemma because it would fire on every `List.map`.
+theorem map_const' (l : Vector α n) (b : β) : map (fun _ => b) l = mkVector n b :=
+  map_const l b
+
+@[simp] theorem set_mkVector_self : (mkVector n a).set i a h = mkVector n a := by
+  rw [← toArray_inj]
+  simp
+
+@[simp] theorem setIfInBounds_mkVector_self : (mkVector n a).setIfInBounds i a = mkVector n a := by
+  rw [← toArray_inj]
+  simp
+
+@[simp] theorem mkVector_append_mkVector : mkVector n a ++ mkVector m a = mkVector (n + m) a := by
+  rw [← toArray_inj]
+  simp
+
+theorem append_eq_mkVector_iff {l₁ : Vector α n} {l₂ : Vector α m} {a : α} :
+    l₁ ++ l₂ = mkVector (n + m) a ↔ l₁ = mkVector n a ∧ l₂ = mkVector m a := by
+  simp [← toArray_inj, Array.append_eq_mkArray_iff]
+
+theorem mkVector_eq_append_iff {l₁ : Vector α n} {l₂ : Vector α m} {a : α} :
+    mkVector (n + m) a = l₁ ++ l₂ ↔ l₁ = mkVector n a ∧ l₂ = mkVector m a := by
+  rw [eq_comm, append_eq_mkVector_iff]
+
+@[simp] theorem map_mkVector : (mkVector n a).map f = mkVector n (f a) := by
+  rw [← toArray_inj]
+  simp
+
+
+@[simp] theorem flatten_mkVector_empty : (mkVector n (#v[] : Vector α 0)).flatten = #v[] := by
+  rw [← toArray_inj]
+  simp
+
+@[simp] theorem flatten_mkVector_singleton : (mkVector n #v[a]).flatten = (mkVector n a).cast (by simp) := by
+  ext i h
+  simp [h]
+
+@[simp] theorem flatten_mkVector_mkVector : (mkVector n (mkVector m a)).flatten = mkVector (n * m) a := by
+  ext i h
+  simp [h]
+
+theorem flatMap_mkArray {β} (f : α → Vector β m) : (mkVector n a).flatMap f = (mkVector n (f a)).flatten := by
+  ext i h
+  simp [h]
+
+@[simp] theorem sum_mkArray_nat (n : Nat) (a : Nat) : (mkVector n a).sum = n * a := by
+  simp [toArray_mkVector]
+
+/-! ### reverse -/
+
+@[simp] theorem reverse_push (as : Vector α n) (a : α) :
+    (as.push a).reverse = (#v[a] ++ as.reverse).cast (by omega) := by
+  rcases as with ⟨as, rfl⟩
+  simp [Array.reverse_push]
+
+@[simp] theorem mem_reverse {x : α} {as : Vector α n} : x ∈ as.reverse ↔ x ∈ as := by
+  cases as
+  simp
+
+@[simp] theorem getElem_reverse (a : Vector α n) (i : Nat) (hi : i < n) :
+    (a.reverse)[i] = a[n - 1 - i] := by
+  rcases a with ⟨a, rfl⟩
+  simp
+
+/-- Variant of `getElem?_reverse` with a hypothesis giving the linear relation between the indices. -/
+theorem getElem?_reverse' {l : Vector α n} (i j) (h : i + j + 1 = n) : l.reverse[i]? = l[j]? := by
+  rcases l with ⟨l, rfl⟩
+  simpa using Array.getElem?_reverse' i j h
+
+@[simp]
+theorem getElem?_reverse {l : Vector α n} {i} (h : i < n) :
+    l.reverse[i]? = l[n - 1 - i]? := by
+  cases l
+  simp_all
+
+@[simp] theorem reverse_reverse (as : Vector α n) : as.reverse.reverse = as := by
+  rcases as with ⟨as, rfl⟩
+  simp [Array.reverse_reverse]
+
+theorem reverse_eq_iff {as bs : Vector α n} : as.reverse = bs ↔ as = bs.reverse := by
+  constructor <;> (rintro rfl; simp)
+
+@[simp] theorem reverse_inj {xs ys : Vector α n} : xs.reverse = ys.reverse ↔ xs = ys := by
+  simp [reverse_eq_iff]
+
+@[simp] theorem reverse_eq_push_iff {xs : Vector α (n + 1)} {ys : Vector α n} {a : α} :
+    xs.reverse = ys.push a ↔ xs = (#v[a] ++ ys.reverse).cast (by omega) := by
+  rcases xs with ⟨xs, h⟩
+  rcases ys with ⟨ys, rfl⟩
+  simp [Array.reverse_eq_push_iff]
+
+@[simp] theorem map_reverse (f : α → β) (l : Vector α n) : l.reverse.map f = (l.map f).reverse := by
+  rcases l with ⟨l, rfl⟩
+  simp [Array.map_reverse]
+
+@[simp] theorem reverse_append (as : Vector α n) (bs : Vector α m) :
+    (as ++ bs).reverse = (bs.reverse ++ as.reverse).cast (by omega) := by
+  rcases as with ⟨as, rfl⟩
+  rcases bs with ⟨bs, rfl⟩
+  simp [Array.reverse_append]
+
+@[simp] theorem reverse_eq_append_iff {xs : Vector α (n + m)} {ys : Vector α n} {zs : Vector α m} :
+    xs.reverse = ys ++ zs ↔ xs = (zs.reverse ++ ys.reverse).cast (by omega) := by
+  cases xs
+  cases ys
+  cases zs
+  simp
+
+/-- Reversing a flatten is the same as reversing the order of parts and reversing all parts. -/
+theorem reverse_flatten (L : Vector (Vector α m) n) :
+    L.flatten.reverse = (L.map reverse).reverse.flatten := by
+  cases L using vector₂_induction
+  simp [Array.reverse_flatten]
+
+/-- Flattening a reverse is the same as reversing all parts and reversing the flattened result. -/
+theorem flatten_reverse (L : Vector (Vector α m) n) :
+    L.reverse.flatten = (L.map reverse).flatten.reverse := by
+  cases L using vector₂_induction
+  simp [Array.flatten_reverse]
+
+theorem reverse_flatMap {β} (l : Vector α n) (f : α → Vector β m) :
+    (l.flatMap f).reverse = l.reverse.flatMap (reverse ∘ f) := by
+  rcases l with ⟨l, rfl⟩
+  simp [Array.reverse_flatMap, Function.comp_def]
+
+theorem flatMap_reverse {β} (l : Vector α n) (f : α → Vector β m) :
+    (l.reverse.flatMap f) = (l.flatMap (reverse ∘ f)).reverse := by
+  rcases l with ⟨l, rfl⟩
+  simp [Array.flatMap_reverse, Function.comp_def]
+
+@[simp] theorem reverse_mkVector (n) (a : α) : reverse (mkVector n a) = mkVector n a := by
+  rw [← toArray_inj]
+  simp
+
 /-! Content below this point has not yet been aligned with `List` and `Array`. -/
 
 @[simp] theorem getElem_ofFn {α n} (f : Fin n → α) (i : Nat) (h : i < n) :
@@ -1725,13 +1963,6 @@ theorem swap_comm (a : Vector α n) {i j : Nat} {hi hj} :
   cases a
   simp
 
-/-! ### reverse -/
-
-@[simp] theorem getElem_reverse (a : Vector α n) (i : Nat) (hi : i < n) :
-    (a.reverse)[i] = a[n - 1 - i] := by
-  rcases a with ⟨a, rfl⟩
-  simp
-
 /-! ### Decidable quantifiers. -/
 
 theorem forall_zero_iff {P : Vector α 0 → Prop} :

src/Init/Grind/Norm.lean

@@ -12,116 +12,105 @@ import Init.ByCases
 namespace Lean.Grind
 /-!
 Normalization theorems for the `grind` tactic.
-
-We are also going to use simproc's in the future.
 -/
 
--- Not
-attribute [grind_norm] Classical.not_not
-
--- Ne
-attribute [grind_norm] ne_eq
-
--- Iff
-@[grind_norm] theorem iff_eq (p q : Prop) : (p ↔ q) = (p = q) := by
+theorem iff_eq (p q : Prop) : (p ↔ q) = (p = q) := by
   by_cases p <;> by_cases q <;> simp [*]
 
--- Eq
-attribute [grind_norm] eq_self heq_eq_eq
-
--- Prop equality
-@[grind_norm] theorem eq_true_eq (p : Prop) : (p = True) = p := by simp
-@[grind_norm] theorem eq_false_eq (p : Prop) : (p = False) = ¬p := by simp
-@[grind_norm] theorem not_eq_prop (p q : Prop) : (¬(p = q)) = (p = ¬q) := by
+theorem eq_true_eq (p : Prop) : (p = True) = p := by simp
+theorem eq_false_eq (p : Prop) : (p = False) = ¬p := by simp
+theorem not_eq_prop (p q : Prop) : (¬(p = q)) = (p = ¬q) := by
   by_cases p <;> by_cases q <;> simp [*]
 
--- True
-attribute [grind_norm] not_true
-
--- False
-attribute [grind_norm] not_false_eq_true
-
 -- Remark: we disabled the following normalization rule because we want this information when implementing splitting heuristics
 -- Implication as a clause
 theorem imp_eq (p q : Prop) : (p → q) = (¬ p ∨ q) := by
   by_cases p <;> by_cases q <;> simp [*]
 
-@[grind_norm] theorem true_imp_eq (p : Prop) : (True → p) = p := by simp
-@[grind_norm] theorem false_imp_eq (p : Prop) : (False → p) = True := by simp
-@[grind_norm] theorem imp_true_eq (p : Prop) : (p → True) = True := by simp
-@[grind_norm] theorem imp_false_eq (p : Prop) : (p → False) = ¬p := by simp
-@[grind_norm] theorem imp_self_eq (p : Prop) : (p → p) = True := by simp
+theorem true_imp_eq (p : Prop) : (True → p) = p := by simp
+theorem false_imp_eq (p : Prop) : (False → p) = True := by simp
+theorem imp_true_eq (p : Prop) : (p → True) = True := by simp
+theorem imp_false_eq (p : Prop) : (p → False) = ¬p := by simp
+theorem imp_self_eq (p : Prop) : (p → p) = True := by simp
 
--- And
-@[grind_norm↓] theorem not_and (p q : Prop) : (¬(p ∧ q)) = (¬p ∨ ¬q) := by
+theorem not_and (p q : Prop) : (¬(p ∧ q)) = (¬p ∨ ¬q) := by
   by_cases p <;> by_cases q <;> simp [*]
-attribute [grind_norm] and_true true_and and_false false_and and_assoc
 
--- Or
-attribute [grind_norm↓] not_or
-attribute [grind_norm] or_true true_or or_false false_or or_assoc
-
--- ite
-attribute [grind_norm] ite_true ite_false
-@[grind_norm↓] theorem not_ite {_ : Decidable p} (q r : Prop) : (¬ite p q r) = ite p (¬q) (¬r) := by
+theorem not_ite {_ : Decidable p} (q r : Prop) : (¬ite p q r) = ite p (¬q) (¬r) := by
   by_cases p <;> simp [*]
 
-@[grind_norm] theorem ite_true_false {_ : Decidable p} : (ite p True False) = p := by
+theorem ite_true_false {_ : Decidable p} : (ite p True False) = p := by
   by_cases p <;> simp
 
-@[grind_norm] theorem ite_false_true {_ : Decidable p} : (ite p False True) = ¬p := by
+theorem ite_false_true {_ : Decidable p} : (ite p False True) = ¬p := by
   by_cases p <;> simp
 
--- Forall
-@[grind_norm↓] theorem not_forall (p : α → Prop) : (¬∀ x, p x) = ∃ x, ¬p x := by simp
-attribute [grind_norm] forall_and
+theorem not_forall (p : α → Prop) : (¬∀ x, p x) = ∃ x, ¬p x := by simp
 
--- Exists
-@[grind_norm↓] theorem not_exists (p : α → Prop) : (¬∃ x, p x) = ∀ x, ¬p x := by simp
-attribute [grind_norm] exists_const exists_or exists_prop exists_and_left exists_and_right
+theorem not_exists (p : α → Prop) : (¬∃ x, p x) = ∀ x, ¬p x := by simp
 
--- Bool cond
-@[grind_norm] theorem cond_eq_ite (c : Bool) (a b : α) : cond c a b = ite c a b := by
+theorem cond_eq_ite (c : Bool) (a b : α) : cond c a b = ite c a b := by
   cases c <;> simp [*]
 
--- Bool or
-attribute [grind_norm]
-  Bool.or_false Bool.or_true Bool.false_or Bool.true_or Bool.or_eq_true Bool.or_assoc
-
--- Bool and
-attribute [grind_norm]
-  Bool.and_false Bool.and_true Bool.false_and Bool.true_and Bool.and_eq_true Bool.and_assoc
-
--- Bool not
-attribute [grind_norm]
-  Bool.not_not
-
--- beq
-attribute [grind_norm] beq_iff_eq
-
--- bne
-attribute [grind_norm] bne_iff_ne
-
--- Bool not eq true/false
-attribute [grind_norm] Bool.not_eq_true Bool.not_eq_false
-
--- decide
-attribute [grind_norm] decide_eq_true_eq decide_not not_decide_eq_true
-
--- Nat LE
-attribute [grind_norm] Nat.le_zero_eq
-
--- Nat/Int LT
-@[grind_norm] theorem Nat.lt_eq (a b : Nat) : (a < b) = (a + 1 ≤ b) := by
+theorem Nat.lt_eq (a b : Nat) : (a < b) = (a + 1 ≤ b) := by
   simp [Nat.lt, LT.lt]
 
-@[grind_norm] theorem Int.lt_eq (a b : Int) : (a < b) = (a + 1 ≤ b) := by
+theorem Int.lt_eq (a b : Int) : (a < b) = (a + 1 ≤ b) := by
   simp [Int.lt, LT.lt]
 
--- GT GE
-attribute [grind_norm] GT.gt GE.ge
+theorem ge_eq [LE α] (a b : α) : (a ≥ b) = (b ≤ a) := rfl
+theorem gt_eq [LT α] (a b : α) : (a > b) = (b < a) := rfl
 
--- Succ
-attribute [grind_norm] Nat.succ_eq_add_one
+init_grind_norm
+  /- Pre theorems -/
+  not_and not_or not_ite not_forall not_exists
+  |
+  /- Post theorems -/
+  Classical.not_not
+  ne_eq iff_eq eq_self heq_eq_eq
+  -- Prop equality
+  eq_true_eq eq_false_eq not_eq_prop
+  -- True
+  not_true
+  -- False
+  not_false_eq_true
+  -- Implication
+  true_imp_eq false_imp_eq imp_true_eq imp_false_eq imp_self_eq
+  -- And
+  and_true true_and and_false false_and and_assoc
+  -- Or
+  or_true true_or or_false false_or or_assoc
+  -- ite
+  ite_true ite_false ite_true_false ite_false_true
+  -- Forall
+  forall_and
+  -- Exists
+  exists_const exists_or exists_prop exists_and_left exists_and_right
+  -- Bool cond
+  cond_eq_ite
+  -- Bool or
+  Bool.or_false Bool.or_true Bool.false_or Bool.true_or Bool.or_eq_true Bool.or_assoc
+  -- Bool and
+  Bool.and_false Bool.and_true Bool.false_and Bool.true_and Bool.and_eq_true Bool.and_assoc
+  -- Bool not
+  Bool.not_not
+  -- beq
+  beq_iff_eq
+  -- bne
+  bne_iff_ne
+  -- Bool not eq true/false
+  Bool.not_eq_true Bool.not_eq_false
+  -- decide
+  decide_eq_true_eq decide_not not_decide_eq_true
+  -- Nat LE
+  Nat.le_zero_eq
+  -- Nat/Int LT
+  Nat.lt_eq
+  -- Nat.succ
+  Nat.succ_eq_add_one
+  -- Int
+  Int.lt_eq
+  -- GT GE
+  ge_eq gt_eq
 
 end Lean.Grind

src/Init/Grind/Tactics.lean

@@ -14,7 +14,9 @@ syntax grindEqRhs  := atomic("=" "_")
 syntax grindBwd    := "←"
 syntax grindFwd    := "→"
 
-syntax (name := grind) "grind" (grindEqBoth <|> grindEqRhs <|> grindEq <|> grindBwd <|> grindFwd)? : attr
+syntax grindThmMod := grindEqBoth <|> grindEqRhs <|> grindEq <|> grindBwd <|> grindFwd
+
+syntax (name := grind) "grind" (grindThmMod)? : attr
 
 end Lean.Parser.Attr
 
@@ -49,6 +51,8 @@ structure Config where
   failures : Nat := 1
   /-- Maximum number of heartbeats (in thousands) the canonicalizer can spend per definitional equality test. -/
   canonHeartbeats : Nat := 1000
+  /-- If `ext` is `true`, `grind` uses extensionality theorems available in the environment. -/
+  ext : Bool := true
   deriving Inhabited, BEq
 
 end Lean.Grind
@@ -59,7 +63,13 @@ namespace Lean.Parser.Tactic
 `grind` tactic and related tactics.
 -/
 
--- TODO: parameters
-syntax (name := grind) "grind" optConfig ("on_failure " term)? : tactic
+syntax grindErase := "-" ident
+syntax grindLemma := (Attr.grindThmMod)? ident
+syntax grindParam := grindErase <|> grindLemma
+
+syntax (name := grind)
+  "grind" optConfig (&" only")?
+  (" [" withoutPosition(grindParam,*) "]")?
+  ("on_failure " term)? : tactic
 
 end Lean.Parser.Tactic

src/Init/Prelude.lean

@@ -150,6 +150,9 @@ It can also be written as `()`.
 /-- Marker for information that has been erased by the code generator. -/
 unsafe axiom lcErased : Type
 
+/-- Marker for type dependency that has been erased by the code generator. -/
+unsafe axiom lcAny : Type
+
 /--
 Auxiliary unsafe constant used by the Compiler when erasing proofs from code.
 

src/Init/Tactics.lean

@@ -1648,17 +1648,6 @@ If there are several with the same priority, it is uses the "most recent one". E
 -/
 syntax (name := simp) "simp" (Tactic.simpPre <|> Tactic.simpPost)? patternIgnore("← " <|> "<- ")? (ppSpace prio)? : attr
 
-/--
-Theorems tagged with the `grind_norm` attribute are used by the `grind` tactic normalizer/pre-processor.
--/
-syntax (name := grind_norm) "grind_norm" (Tactic.simpPre <|> Tactic.simpPost)? (ppSpace prio)? : attr
-
-/--
-Simplification procedures tagged with the `grind_norm_proc` attribute are used by the `grind` tactic normalizer/pre-processor.
--/
-syntax (name := grind_norm_proc) "grind_norm_proc" (Tactic.simpPre <|> Tactic.simpPost)? : attr
-
-
 /-- The possible `norm_cast` kinds: `elim`, `move`, or `squash`. -/
 syntax normCastLabel := &"elim" <|> &"move" <|> &"squash"
 

src/Lean/AddDecl.lean

@@ -14,21 +14,54 @@ register_builtin_option debug.skipKernelTC : Bool := {
   descr    := "skip kernel type checker. WARNING: setting this option to true may compromise soundness because your proofs will not be checked by the Lean kernel"
 }
 
-def Environment.addDecl (env : Environment) (opts : Options) (decl : Declaration)
-    (cancelTk? : Option IO.CancelToken := none) : Except KernelException Environment :=
+/-- Adds given declaration to the environment, respecting `debug.skipKernelTC`. -/
+def Kernel.Environment.addDecl (env : Environment) (opts : Options) (decl : Declaration)
+    (cancelTk? : Option IO.CancelToken := none) : Except Exception Environment :=
   if debug.skipKernelTC.get opts then
     addDeclWithoutChecking env decl
   else
     addDeclCore env (Core.getMaxHeartbeats opts).toUSize decl cancelTk?
 
+private def Environment.addDeclAux (env : Environment) (opts : Options) (decl : Declaration)
+    (cancelTk? : Option IO.CancelToken := none) : Except Kernel.Exception Environment :=
+  env.addDeclCore (Core.getMaxHeartbeats opts).toUSize decl cancelTk? (!debug.skipKernelTC.get opts)
+
+@[deprecated "use `Lean.addDecl` instead to ensure new namespaces are registered" (since := "2024-12-03")]
+def Environment.addDecl (env : Environment) (opts : Options) (decl : Declaration)
+    (cancelTk? : Option IO.CancelToken := none) : Except Kernel.Exception Environment :=
+  Environment.addDeclAux env opts decl cancelTk?
+
+private def isNamespaceName : Name → Bool
+  | .str .anonymous _ => true
+  | .str p _          => isNamespaceName p
+  | _                 => false
+
+private def registerNamePrefixes (env : Environment) (name : Name) : Environment :=
+  match name with
+    | .str _ s =>
+      if s.get 0 == '_' then
+        -- Do not register namespaces that only contain internal declarations.
+        env
+      else
+        go env name
+    | _ => env
+where go env
+  | .str p _ => if isNamespaceName p then go (env.registerNamespace p) p else env
+  | _        => env
+
 def addDecl (decl : Declaration) : CoreM Unit := do
   profileitM Exception "type checking" (← getOptions) do
-    withTraceNode `Kernel (fun _ => return m!"typechecking declaration") do
+    let mut env ← withTraceNode `Kernel (fun _ => return m!"typechecking declaration") do
       if !(← MonadLog.hasErrors) && decl.hasSorry then
         logWarning "declaration uses 'sorry'"
-      match (← getEnv).addDecl (← getOptions) decl (← read).cancelTk? with
-      | .ok    env => setEnv env
-      | .error ex  => throwKernelException ex
+      (← getEnv).addDeclAux (← getOptions) decl (← read).cancelTk? |> ofExceptKernelException
+
+    -- register namespaces for newly added constants; this used to be done by the kernel itself
+    -- but that is incompatible with moving it to a separate task
+    env := decl.getNames.foldl registerNamePrefixes env
+    if let .inductDecl _ _ types _ := decl then
+      env := types.foldl (registerNamePrefixes · <| ·.name ++ `rec) env
+    setEnv env
 
 def addAndCompile (decl : Declaration) : CoreM Unit := do
   addDecl decl

src/Lean/Compiler/LCNF/ToMono.lean

@@ -150,18 +150,7 @@ where
 
 def toMono : Pass where
   name     := `toMono
-  run      := fun decls => do
-    let decls ← decls.filterM fun decl => do
-      if hasLocalInst decl.type then
-        /-
-        Declaration is a "template" for the code specialization pass.
-        So, we should delete it before going to next phase.
-        -/
-        decl.erase
-        return false
-      else
-        return true
-    decls.mapM (·.toMono)
+  run      := (·.mapM (·.toMono))
   phase    := .base
   phaseOut := .mono
 

src/Lean/CoreM.lean

@@ -515,7 +515,7 @@ register_builtin_option compiler.enableNew : Bool := {
 opaque compileDeclsNew (declNames : List Name) : CoreM Unit
 
 @[extern "lean_compile_decls"]
-opaque compileDeclsOld (env : Environment) (opt : @& Options) (decls : @& List Name) : Except KernelException Environment
+opaque compileDeclsOld (env : Environment) (opt : @& Options) (decls : @& List Name) : Except Kernel.Exception Environment
 
 def compileDecl (decl : Declaration) : CoreM Unit := do
   let opts ← getOptions
@@ -526,7 +526,7 @@ def compileDecl (decl : Declaration) : CoreM Unit := do
     return compileDeclsOld (← getEnv) opts decls
   match res with
   | Except.ok env => setEnv env
-  | Except.error (KernelException.other msg) =>
+  | Except.error (.other msg) =>
     checkUnsupported decl -- Generate nicer error message for unsupported recursors and axioms
     throwError msg
   | Except.error ex =>
@@ -538,7 +538,7 @@ def compileDecls (decls : List Name) : CoreM Unit := do
     compileDeclsNew decls
   match compileDeclsOld (← getEnv) opts decls with
   | Except.ok env   => setEnv env
-  | Except.error (KernelException.other msg) =>
+  | Except.error (.other msg) =>
     throwError msg
   | Except.error ex =>
     throwKernelException ex

src/Lean/Data/NameTrie.lean

@@ -54,6 +54,10 @@ instance : EmptyCollection (NameTrie β) where
 def NameTrie.find? (t : NameTrie β) (k : Name) : Option β :=
   PrefixTree.find? t (toKey k)
 
+@[inline, inherit_doc PrefixTree.findLongestPrefix?]
+def NameTrie.findLongestPrefix? (t : NameTrie β) (k : Name) : Option β :=
+  PrefixTree.findLongestPrefix? t (toKey k)
+
 @[inline]
 def NameTrie.foldMatchingM [Monad m] (t : NameTrie β) (k : Name) (init : σ) (f : β → σ → m σ) : m σ :=
   PrefixTree.foldMatchingM t (toKey k) init f

src/Lean/Data/PrefixTree.lean

@@ -48,6 +48,17 @@ partial def find? (t : PrefixTreeNode α β) (cmp : α → α → Ordering) (k :
       | some t => loop t ks
   loop t k
 
+/-- Returns the the value of the longest key in `t` that is a prefix of `k`, if any. -/
+@[specialize]
+partial def findLongestPrefix? (t : PrefixTreeNode α β) (cmp : α → α → Ordering) (k : List α) : Option β :=
+  let rec loop acc?
+    | PrefixTreeNode.Node val _, [] => val <|> acc?
+    | PrefixTreeNode.Node val m, k :: ks =>
+      match RBNode.find cmp m k with
+      | none   => val
+      | some t => loop (val <|> acc?) t ks
+  loop none t k
+
 @[specialize]
 partial def foldMatchingM [Monad m] (t : PrefixTreeNode α β) (cmp : α → α → Ordering) (k : List α) (init : σ) (f : β → σ → m σ) : m σ :=
   let rec fold : PrefixTreeNode α β → σ → m σ
@@ -92,6 +103,10 @@ def PrefixTree.insert (t : PrefixTree α β p) (k : List α) (v : β) : PrefixTr
 def PrefixTree.find? (t : PrefixTree α β p) (k : List α) : Option β :=
   t.val.find? p k
 
+@[inline, inherit_doc PrefixTreeNode.findLongestPrefix?]
+def PrefixTree.findLongestPrefix? (t : PrefixTree α β p) (k : List α) : Option β :=
+  t.val.findLongestPrefix? p k
+
 @[inline]
 def PrefixTree.foldMatchingM [Monad m] (t : PrefixTree α β p) (k : List α) (init : σ) (f : β → σ → m σ) : m σ :=
   t.val.foldMatchingM p k init f

src/Lean/Declaration.lean

@@ -193,6 +193,19 @@ def Declaration.definitionVal! : Declaration → DefinitionVal
   | .defnDecl val => val
   | _ => panic! "Expected a `Declaration.defnDecl`."
 
+/--
+Returns all top-level names to be defined by adding this declaration to the environment. This does
+not include auxiliary definitions such as projections.
+-/
+def Declaration.getNames : Declaration → List Name
+  | .axiomDecl val          => [val.name]
+  | .defnDecl val           => [val.name]
+  | .thmDecl val            => [val.name]
+  | .opaqueDecl val         => [val.name]
+  | .quotDecl               => [``Quot, ``Quot.mk, ``Quot.lift, ``Quot.ind]
+  | .mutualDefnDecl defns   => defns.map (·.name)
+  | .inductDecl _ _ types _ => types.map (·.name)
+
 @[specialize] def Declaration.foldExprM {α} {m : Type → Type} [Monad m] (d : Declaration) (f : α → Expr → m α) (a : α) : m α :=
   match d with
   | .quotDecl                                        => pure a
@@ -469,6 +482,10 @@ def isInductive : ConstantInfo → Bool
   | .inductInfo _ => true
   | _             => false
 
+def isDefinition : ConstantInfo → Bool
+  | .defnInfo _ => true
+  | _           => false
+
 def isTheorem : ConstantInfo → Bool
   | .thmInfo _ => true
   | _          => false

src/Lean/Elab/BuiltinCommand.lean

@@ -124,9 +124,7 @@ private partial def elabChoiceAux (cmds : Array Syntax) (i : Nat) : CommandElabM
   n[1].forArgsM addUnivLevel
 
 @[builtin_command_elab «init_quot»] def elabInitQuot : CommandElab := fun _ => do
-  match (← getEnv).addDecl (← getOptions) Declaration.quotDecl with
-  | Except.ok env   => setEnv env
-  | Except.error ex => throwError (ex.toMessageData (← getOptions))
+  liftCoreM <| addDecl Declaration.quotDecl
 
 @[builtin_command_elab «export»] def elabExport : CommandElab := fun stx => do
   let `(export $ns ($ids*)) := stx | throwUnsupportedSyntax
@@ -294,7 +292,7 @@ def failIfSucceeds (x : CommandElabM Unit) : CommandElabM Unit := do
     modify fun s => { s with messages := {} };
     pure messages
   let restoreMessages (prevMessages : MessageLog) : CommandElabM Unit := do
-    modify fun s => { s with messages := prevMessages ++ s.messages.errorsToWarnings }
+    modify fun s => { s with messages := prevMessages ++ s.messages.errorsToInfos }
   let prevMessages ← resetMessages
   let succeeded ← try
     x

src/Lean/Elab/Structure.lean

@@ -681,7 +681,7 @@ private partial def checkResultingUniversesForFields (fieldInfos : Array StructF
       throwErrorAt info.ref msg
 
 @[extern "lean_mk_projections"]
-private opaque mkProjections (env : Environment) (structName : Name) (projs : List Name) (isClass : Bool) : Except KernelException Environment
+private opaque mkProjections (env : Environment) (structName : Name) (projs : List Name) (isClass : Bool) : Except Kernel.Exception Environment
 
 private def addProjections (r : ElabHeaderResult) (fieldInfos : Array StructFieldInfo) : TermElabM Unit := do
   if r.type.isProp then

src/Lean/Elab/Tactic/Ext.lean

@@ -5,6 +5,7 @@ Authors: Gabriel Ebner, Mario Carneiro
 -/
 prelude
 import Init.Ext
+import Lean.Meta.Tactic.Ext
 import Lean.Elab.DeclarationRange
 import Lean.Elab.Tactic.RCases
 import Lean.Elab.Tactic.Repeat
@@ -174,65 +175,8 @@ def realizeExtIffTheorem (extName : Name) : Elab.Command.CommandElabM Name := do
 ### Attribute
 -/
 
-/-- Information about an extensionality theorem, stored in the environment extension. -/
-structure ExtTheorem where
-  /-- Declaration name of the extensionality theorem. -/
-  declName : Name
-  /-- Priority of the extensionality theorem. -/
-  priority : Nat
-  /--
-  Key in the discrimination tree,
-  for the type in which the extensionality theorem holds.
-  -/
-  keys : Array DiscrTree.Key
-  deriving Inhabited, Repr, BEq, Hashable
-
-/-- The state of the `ext` extension environment -/
-structure ExtTheorems where
-  /-- The tree of `ext` extensions. -/
-  tree   : DiscrTree ExtTheorem := {}
-  /-- Erased `ext`s via `attribute [-ext]`. -/
-  erased  : PHashSet Name := {}
-  deriving Inhabited
-
-/-- The environment extension to track `@[ext]` theorems. -/
-builtin_initialize extExtension :
-    SimpleScopedEnvExtension ExtTheorem ExtTheorems ←
-  registerSimpleScopedEnvExtension {
-    addEntry := fun { tree, erased } thm =>
-      { tree := tree.insertCore thm.keys thm, erased := erased.erase thm.declName }
-    initial := {}
-  }
-
-/-- Gets the list of `@[ext]` theorems corresponding to the key `ty`,
-ordered from high priority to low. -/
-@[inline] def getExtTheorems (ty : Expr) : MetaM (Array ExtTheorem) := do
-  let extTheorems := extExtension.getState (← getEnv)
-  let arr ← extTheorems.tree.getMatch ty
-  let erasedArr := arr.filter fun thm => !extTheorems.erased.contains thm.declName
-  -- Using insertion sort because it is stable and the list of matches should be mostly sorted.
-  -- Most ext theorems have default priority.
-  return erasedArr.insertionSort (·.priority < ·.priority) |>.reverse
-
-/--
-Erases a name marked `ext` by adding it to the state's `erased` field and
-removing it from the state's list of `Entry`s.
-
-This is triggered by `attribute [-ext] name`.
--/
-def ExtTheorems.eraseCore (d : ExtTheorems) (declName : Name) : ExtTheorems :=
- { d with erased := d.erased.insert declName }
-
-/--
-Erases a name marked as a `ext` attribute.
-Check that it does in fact have the `ext` attribute by making sure it names a `ExtTheorem`
-found somewhere in the state's tree, and is not erased.
--/
-def ExtTheorems.erase [Monad m] [MonadError m] (d : ExtTheorems) (declName : Name) :
-    m ExtTheorems := do
-  unless d.tree.containsValueP (·.declName == declName) && !d.erased.contains declName do
-    throwError "'{declName}' does not have [ext] attribute"
-  return d.eraseCore declName
+abbrev extExtension := Meta.Ext.extExtension
+abbrev getExtTheorems := Meta.Ext.getExtTheorems
 
 builtin_initialize registerBuiltinAttribute {
   name := `ext

src/Lean/Elab/Tactic/Grind.lean

@@ -34,8 +34,67 @@ def elabGrindPattern : CommandElab := fun stx => do
         Grind.addEMatchTheorem declName xs.size patterns.toList
   | _ => throwUnsupportedSyntax
 
-def grind (mvarId : MVarId) (config : Grind.Config) (mainDeclName : Name) (fallback : Grind.Fallback) : MetaM Unit := do
-  let goals ← Grind.main mvarId config mainDeclName fallback
+open Command Term in
+@[builtin_command_elab Lean.Parser.Command.initGrindNorm]
+def elabInitGrindNorm : CommandElab := fun stx =>
+  match stx with
+  | `(init_grind_norm $pre:ident* | $post*) =>
+    Command.liftTermElabM do
+      let pre ← pre.mapM fun id => realizeGlobalConstNoOverloadWithInfo id
+      let post ← post.mapM fun id => realizeGlobalConstNoOverloadWithInfo id
+      Grind.registerNormTheorems pre post
+  | _ => throwUnsupportedSyntax
+
+def elabGrindParams (params : Grind.Params) (ps :  TSyntaxArray ``Parser.Tactic.grindParam) : MetaM Grind.Params := do
+  let mut params := params
+  for p in ps do
+    match p with
+    | `(Parser.Tactic.grindParam| - $id:ident) =>
+      let declName ← realizeGlobalConstNoOverloadWithInfo id
+      if (← isInductivePredicate declName) then
+        throwErrorAt p "NIY"
+      else
+        params := { params with ematch := (← params.ematch.eraseDecl declName) }
+    | `(Parser.Tactic.grindParam| $[$mod?:grindThmMod]? $id:ident) =>
+      let declName ← realizeGlobalConstNoOverloadWithInfo id
+      let kind ← if let some mod := mod? then Grind.getTheoremKindCore mod else pure .default
+      if (← isInductivePredicate declName) then
+        throwErrorAt p "NIY"
+      else
+        let info ← getConstInfo declName
+        match info with
+        | .thmInfo _ =>
+          if kind == .eqBoth then
+            params := { params with extra := params.extra.push (← Grind.mkEMatchTheoremForDecl declName .eqLhs) }
+            params := { params with extra := params.extra.push (← Grind.mkEMatchTheoremForDecl declName .eqRhs) }
+          else
+            params := { params with extra := params.extra.push (← Grind.mkEMatchTheoremForDecl declName kind) }
+        | .defnInfo _ =>
+          if (← isReducible declName) then
+            throwErrorAt p "`{declName}` is a reducible definition, `grind` automatically unfolds them"
+          if kind != .eqLhs && kind != .default then
+            throwErrorAt p "invalid `grind` parameter, `{declName}` is a definition, the only acceptable (and redundant) modifier is '='"
+          let some thms ← Grind.mkEMatchEqTheoremsForDef? declName
+            | throwErrorAt p "failed to genereate equation theorems for `{declName}`"
+          params := { params with extra := params.extra ++ thms.toPArray' }
+        | _ =>
+          throwErrorAt p "invalid `grind` parameter, `{declName}` is not a theorem, definition, or inductive type"
+    | _ => throwError "unexpected `grind` parameter{indentD p}"
+  return params
+
+def mkGrindParams (config : Grind.Config) (only : Bool) (ps :  TSyntaxArray ``Parser.Tactic.grindParam) : MetaM Grind.Params := do
+  let params ← Grind.mkParams config
+  let ematch ← if only then pure {} else Grind.getEMatchTheorems
+  let params := { params with ematch }
+  elabGrindParams params ps
+
+def grind
+    (mvarId : MVarId) (config : Grind.Config)
+    (only : Bool)
+    (ps   :  TSyntaxArray ``Parser.Tactic.grindParam)
+    (mainDeclName : Name) (fallback : Grind.Fallback) : MetaM Unit := do
+  let params ← mkGrindParams config only ps
+  let goals ← Grind.main mvarId params mainDeclName fallback
   unless goals.isEmpty do
     throwError "`grind` failed\n{← Grind.goalsToMessageData goals config}"
 
@@ -56,14 +115,16 @@ private def elabFallback (fallback? : Option Term) : TermElabM (Grind.GoalM Unit
     pure auxDeclName
   unsafe evalConst (Grind.GoalM Unit) auxDeclName
 
-@[builtin_tactic Lean.Parser.Tactic.grind] def evalApplyRfl : Tactic := fun stx => do
+@[builtin_tactic Lean.Parser.Tactic.grind] def evalGrind : Tactic := fun stx => do
   match stx with
-  | `(tactic| grind $config:optConfig $[on_failure $fallback?]?) =>
+  | `(tactic| grind $config:optConfig $[only%$only]?  $[ [$params:grindParam,*] ]? $[on_failure $fallback?]?) =>
     let fallback ← elabFallback fallback?
+    let only := only.isSome
+    let params := if let some params := params then params.getElems else #[]
     logWarningAt stx "The `grind` tactic is experimental and still under development. Avoid using it in production projects"
     let declName := (← Term.getDeclName?).getD `_grind
     let config ← elabGrindConfig config
-    withMainContext do liftMetaFinishingTactic (grind · config declName fallback)
+    withMainContext do liftMetaFinishingTactic (grind · config only params declName fallback)
   | _ => throwUnsupportedSyntax
 
 end Lean.Elab.Tactic

src/Lean/Environment.lean

@@ -7,8 +7,10 @@ prelude
 import Init.Control.StateRef
 import Init.Data.Array.BinSearch
 import Init.Data.Stream
+import Init.System.Promise
 import Lean.ImportingFlag
 import Lean.Data.HashMap
+import Lean.Data.NameTrie
 import Lean.Data.SMap
 import Lean.Declaration
 import Lean.LocalContext
@@ -16,6 +18,50 @@ import Lean.Util.Path
 import Lean.Util.FindExpr
 import Lean.Util.Profile
 import Lean.Util.InstantiateLevelParams
+import Lean.PrivateName
+
+/-!
+# Note [Environment Branches]
+
+The kernel environment type `Lean.Kernel.Environment` enforces a linear order on the addition of
+declarations: `addDeclCore` takes an environment and returns a new one, assuming type checking
+succeeded. On the other hand, the metaprogramming-level `Lean.Environment` wrapper must allow for
+*branching* environment transformations so that multiple declarations can be elaborated
+concurrently while still being able to access information about preceding declarations that have
+also been branched out as soon as they are available.
+
+The basic function to introduce such branches is `addConstAsync`, which takes an environment and
+returns a structure containing two environments: one for the "main" branch that can be used in
+further branching and eventually contains all the declarations of the file and one for the "async"
+branch that can be used concurrently to the main branch to elaborate and add the declaration for
+which the branch was introduced. Branches are "joined" back together implicitly via the kernel
+environment, which as mentioned cannot be changed concurrently: when the main branch first tries to
+access it, evaluation is blocked until the kernel environment on the async branch is complete.
+Thus adding two declarations A and B concurrently can be visualized like this:
+```text
+o addConstAsync A
+|\
+| \
+|  \
+o addConstAsync B
+|\   \
+| \   o elaborate A
+|  \  |
+|   o elaborate B
+|   | |
+|   | o addDeclCore A
+|   |/
+|   o addDeclCore B
+|  /
+| /
+|/
+o .olean serialization calls Environment.toKernelEnv
+```
+While each edge represents a `Lean.Environment` that has its own view of the state of the module,
+the kernel environment really lives only in the right-most path, with all other paths merely holding
+an unfulfilled `Task` representing it and where forcing that task leads to the back-edges joining
+paths back together.
+-/
 
 namespace Lean
 /-- Opaque environment extension state. -/
@@ -88,11 +134,6 @@ structure EnvironmentHeader where
   -/
   trustLevel   : UInt32       := 0
   /--
-  `quotInit = true` if the command `init_quot` has already been executed for the environment, and
-  `Quot` declarations have been added to the environment.
-  -/
-  quotInit     : Bool         := false
-  /--
   Name of the module being compiled.
   -/
   mainModule   : Name         := default
@@ -106,6 +147,15 @@ structure EnvironmentHeader where
   moduleData   : Array ModuleData := #[]
   deriving Nonempty
 
+namespace Kernel
+
+structure Diagnostics where
+  /-- Number of times each declaration has been unfolded by the kernel. -/
+  unfoldCounter : PHashMap Name Nat := {}
+  /-- If `enabled = true`, kernel records declarations that have been unfolded. -/
+  enabled : Bool := false
+  deriving Inhabited
+
 /--
 An environment stores declarations provided by the user. The kernel
 currently supports different kinds of declarations such as definitions, theorems,
@@ -121,10 +171,33 @@ declared by users are stored in an environment extension. Users can declare new
 using meta-programming.
 -/
 structure Environment where
-  /-- The constructor of `Environment` is private to protect against modification
-  that bypasses the kernel. -/
+  /--
+  The constructor of `Environment` is private to protect against modification that bypasses the
+  kernel.
+  -/
   private mk ::
   /--
+  Mapping from constant name to `ConstantInfo`. It contains all constants (definitions, theorems,
+  axioms, etc) that have been already type checked by the kernel.
+  -/
+  constants   : ConstMap
+  /--
+  `quotInit = true` if the command `init_quot` has already been executed for the environment, and
+  `Quot` declarations have been added to the environment. When the flag is set, the type checker can
+  assume that the `Quot` declarations in the environment have indeed been added by the kernel and
+  not by the user.
+  -/
+  quotInit    : Bool := false
+  /--
+  Diagnostic information collected during kernel execution.
+
+  Remark: We store kernel diagnostic information in an environment field to simplify the interface
+  with the kernel implemented in C/C++. Thus, we can only track declarations in methods, such as
+  `addDecl`, which return a new environment. `Kernel.isDefEq` and `Kernel.whnf` do not update the
+  statistics. We claim this is ok since these methods are mainly used for debugging.
+  -/
+  diagnostics : Diagnostics := {}
+  /--
   Mapping from constant name to module (index) where constant has been declared.
   Recall that a Lean file has a header where previously compiled modules can be imported.
   Each imported module has a unique `ModuleIdx`.
@@ -134,96 +207,23 @@ structure Environment where
   the field `constants`. These auxiliary constants are invisible to the Lean kernel and elaborator.
   Only the code generator uses them.
   -/
-  const2ModIdx : Std.HashMap Name ModuleIdx
-  /--
-  Mapping from constant name to `ConstantInfo`. It contains all constants (definitions, theorems, axioms, etc)
-  that have been already type checked by the kernel.
-  -/
-  constants    : ConstMap
+  const2ModIdx            : Std.HashMap Name ModuleIdx
   /--
   Environment extensions. It also includes user-defined extensions.
   -/
-  extensions   : Array EnvExtensionState
+  private extensions      : Array EnvExtensionState
   /--
   Constant names to be saved in the field `extraConstNames` at `ModuleData`.
   It contains auxiliary declaration names created by the code generator which are not in `constants`.
   When importing modules, we want to insert them at `const2ModIdx`.
   -/
-  extraConstNames : NameSet
-  /-- The header contains additional information that is not updated often. -/
-  header       : EnvironmentHeader := {}
-  deriving Nonempty
+  private extraConstNames : NameSet
+  /-- The header contains additional information that is set at import time. -/
+  header                  : EnvironmentHeader := {}
+deriving Nonempty
 
-namespace Environment
-
-private def addAux (env : Environment) (cinfo : ConstantInfo) : Environment :=
-  { env with constants := env.constants.insert cinfo.name cinfo }
-
-/--
-Save an extra constant name that is used to populate `const2ModIdx` when we import
-.olean files. We use this feature to save in which module an auxiliary declaration
-created by the code generator has been created.
--/
-def addExtraName (env : Environment) (name : Name) : Environment :=
-  if env.constants.contains name then
-    env
-  else
-    { env with extraConstNames := env.extraConstNames.insert name }
-
-@[export lean_environment_find]
-def find? (env : Environment) (n : Name) : Option ConstantInfo :=
-  /- It is safe to use `find'` because we never overwrite imported declarations. -/
-  env.constants.find?' n
-
-def contains (env : Environment) (n : Name) : Bool :=
-  env.constants.contains n
-
-def imports (env : Environment) : Array Import :=
-  env.header.imports
-
-def allImportedModuleNames (env : Environment) : Array Name :=
-  env.header.moduleNames
-
-@[export lean_environment_set_main_module]
-def setMainModule (env : Environment) (m : Name) : Environment :=
-  { env with header := { env.header with mainModule := m } }
-
-@[export lean_environment_main_module]
-def mainModule (env : Environment) : Name :=
-  env.header.mainModule
-
-@[export lean_environment_mark_quot_init]
-private def markQuotInit (env : Environment) : Environment :=
-  { env with header := { env.header with quotInit := true } }
-
-@[export lean_environment_quot_init]
-private def isQuotInit (env : Environment) : Bool :=
-  env.header.quotInit
-
-@[export lean_environment_trust_level]
-private def getTrustLevel (env : Environment) : UInt32 :=
-  env.header.trustLevel
-
-def getModuleIdxFor? (env : Environment) (declName : Name) : Option ModuleIdx :=
-  env.const2ModIdx[declName]?
-
-def isConstructor (env : Environment) (declName : Name) : Bool :=
-  match env.find? declName with
-  | some (.ctorInfo _) => true
-  | _                  => false
-
-def isSafeDefinition (env : Environment) (declName : Name) : Bool :=
-  match env.find? declName with
-  | some (.defnInfo { safety := .safe, .. }) => true
-  | _ => false
-
-def getModuleIdx? (env : Environment) (moduleName : Name) : Option ModuleIdx :=
-  env.header.moduleNames.findIdx? (· == moduleName)
-
-end Environment
-
-/-- Exceptions that can be raised by the Kernel when type checking new declarations. -/
-inductive KernelException where
+/-- Exceptions that can be raised by the kernel when type checking new declarations. -/
+inductive Exception where
   | unknownConstant  (env : Environment) (name : Name)
   | alreadyDeclared  (env : Environment) (name : Name)
   | declTypeMismatch (env : Environment) (decl : Declaration) (givenType : Expr)
@@ -244,21 +244,500 @@ inductive KernelException where
 
 namespace Environment
 
-/--
-Type check given declaration and add it to the environment
--/
+@[export lean_environment_find]
+def find? (env : Environment) (n : Name) : Option ConstantInfo :=
+  /- It is safe to use `find'` because we never overwrite imported declarations. -/
+  env.constants.find?' n
+
+@[export lean_environment_mark_quot_init]
+private def markQuotInit (env : Environment) : Environment :=
+  { env with quotInit := true }
+
+@[export lean_environment_quot_init]
+private def isQuotInit (env : Environment) : Bool :=
+  env.quotInit
+
+/-- Type check given declaration and add it to the environment -/
 @[extern "lean_add_decl"]
 opaque addDeclCore (env : Environment) (maxHeartbeats : USize) (decl : @& Declaration)
-  (cancelTk? : @& Option IO.CancelToken) : Except KernelException Environment
+  (cancelTk? : @& Option IO.CancelToken) : Except Exception Environment
 
 /--
 Add declaration to kernel without type checking it.
+
 **WARNING** This function is meant for temporarily working around kernel performance issues.
 It compromises soundness because, for example, a buggy tactic may produce an invalid proof,
 and the kernel will not catch it if the new option is set to true.
 -/
 @[extern "lean_add_decl_without_checking"]
-opaque addDeclWithoutChecking (env : Environment) (decl : @& Declaration) : Except KernelException Environment
+opaque addDeclWithoutChecking (env : Environment) (decl : @& Declaration) : Except Exception Environment
+
+@[export lean_environment_add]
+private def add (env : Environment) (cinfo : ConstantInfo) : Environment :=
+  { env with constants := env.constants.insert cinfo.name cinfo }
+
+@[export lean_kernel_diag_is_enabled]
+def Diagnostics.isEnabled (d : Diagnostics) : Bool :=
+  d.enabled
+
+/-- Enables/disables kernel diagnostics. -/
+def enableDiag (env : Environment) (flag : Bool) : Environment :=
+  { env with diagnostics.enabled := flag }
+
+def isDiagnosticsEnabled (env : Environment) : Bool :=
+  env.diagnostics.enabled
+
+def resetDiag (env : Environment) : Environment :=
+  { env with diagnostics.unfoldCounter := {} }
+
+@[export lean_kernel_record_unfold]
+def Diagnostics.recordUnfold (d : Diagnostics) (declName : Name) : Diagnostics :=
+  if d.enabled then
+    let cNew := if let some c := d.unfoldCounter.find? declName then c + 1 else 1
+    { d with unfoldCounter := d.unfoldCounter.insert declName cNew }
+  else
+    d
+
+@[export lean_kernel_get_diag]
+def getDiagnostics (env : Environment) : Diagnostics :=
+  env.diagnostics
+
+@[export lean_kernel_set_diag]
+def setDiagnostics (env : Environment) (diag : Diagnostics) : Environment :=
+  { env with diagnostics := diag}
+
+end Kernel.Environment
+
+@[deprecated Kernel.Exception (since := "2024-12-12")]
+abbrev KernelException := Kernel.Exception
+
+inductive ConstantKind where
+  | defn | thm | «axiom» | «opaque» | quot | induct | ctor | recursor
+deriving Inhabited, BEq, Repr
+
+def ConstantKind.ofConstantInfo : ConstantInfo → ConstantKind
+  | .defnInfo   _ => .defn
+  | .thmInfo    _ => .thm
+  | .axiomInfo  _ => .axiom
+  | .opaqueInfo _ => .opaque
+  | .quotInfo   _ => .quot
+  | .inductInfo _ => .induct
+  | .ctorInfo   _ => .ctor
+  | .recInfo    _ => .recursor
+
+/-- `ConstantInfo` variant that allows for asynchronous filling of components via tasks. -/
+structure AsyncConstantInfo where
+  /-- The declaration name, known immediately. -/
+  name      : Name
+  /-- The kind of the constant, known immediately. -/
+  kind      : ConstantKind
+  /-- The "signature" including level params and type, potentially filled asynchronously. -/
+  sig       : Task ConstantVal
+  /-- The final, complete constant info, potentially filled asynchronously. -/
+  constInfo : Task ConstantInfo
+
+namespace AsyncConstantInfo
+
+def toConstantVal (c : AsyncConstantInfo) : ConstantVal :=
+  c.sig.get
+
+def toConstantInfo (c : AsyncConstantInfo) : ConstantInfo :=
+  c.constInfo.get
+
+def ofConstantInfo (c : ConstantInfo) : AsyncConstantInfo where
+  name := c.name
+  kind := .ofConstantInfo c
+  sig := .pure c.toConstantVal
+  constInfo := .pure c
+
+end AsyncConstantInfo
+
+/--
+Information about the current branch of the environment representing asynchronous elaboration.
+-/
+structure AsyncContext where
+  /--
+  Name of the declaration asynchronous elaboration was started for. All constants added to this
+  environment branch must have the name as a prefix, after erasing macro scopes and private name
+  prefixes.
+  -/
+  declPrefix : Name
+deriving Nonempty
+
+/--
+Checks whether a declaration named `n` may be added to the environment in the given context. See
+also `AsyncContext.declPrefix`.
+-/
+def AsyncContext.mayContain (ctx : AsyncContext) (n : Name) : Bool :=
+  ctx.declPrefix.isPrefixOf <| privateToUserName n.eraseMacroScopes
+
+/--
+Constant info and environment extension states eventually resulting from async elaboration.
+-/
+structure AsyncConst where
+  constInfo : AsyncConstantInfo
+  /--
+  Reported extension state eventually fulfilled by promise; may be missing for tasks (e.g. kernel
+  checking) that can eagerly guarantee they will not report any state.
+  -/
+  exts?     : Option (Task (Array EnvExtensionState))
+
+/-- Data structure holding a sequence of `AsyncConst`s optimized for efficient access. -/
+structure AsyncConsts where
+  toArray : Array AsyncConst := #[]
+  /-- Map from declaration name to const for fast direct access. -/
+  private map : NameMap AsyncConst := {}
+  /-- Trie of declaration names without private name prefixes for fast longest-prefix access. -/
+  private normalizedTrie : NameTrie AsyncConst := {}
+deriving Inhabited
+
+def AsyncConsts.add (aconsts : AsyncConsts) (aconst : AsyncConst) : AsyncConsts :=
+  { aconsts with
+    toArray := aconsts.toArray.push aconst
+    map := aconsts.map.insert aconst.constInfo.name aconst
+    normalizedTrie := aconsts.normalizedTrie.insert (privateToUserName aconst.constInfo.name) aconst
+  }
+
+def AsyncConsts.find? (aconsts : AsyncConsts) (declName : Name) : Option AsyncConst :=
+  aconsts.map.find? declName
+
+/-- Checks whether the name of any constant in the collection is a prefix of `declName`. -/
+def AsyncConsts.hasPrefix (aconsts : AsyncConsts) (declName : Name) : Bool :=
+  -- as macro scopes are a strict suffix,
+  aconsts.normalizedTrie.findLongestPrefix? (privateToUserName declName.eraseMacroScopes) |>.isSome
+
+/--
+Elaboration-specific extension of `Kernel.Environment` that adds tracking of asynchronously
+elaborated declarations.
+-/
+structure Environment where
+  /-
+  Like with `Kernel.Environment`, this constructor is private to protect consistency of the
+  environment, though there are no soundness concerns in this case given that it is used purely for
+  elaboration.
+  -/
+  private mk ::
+  /--
+  Kernel environment not containing any asynchronously elaborated declarations. Also stores
+  environment extension state for the current branch of the environment.
+
+  Ignoring extension state, this is guaranteed to be some prior version of `checked` that is eagerly
+  available. Thus we prefer taking information from it instead of `checked` whenever possible.
+  -/
+  checkedWithoutAsync : Kernel.Environment
+  /--
+  Kernel environment task that is fulfilled when all asynchronously elaborated declarations are
+  finished, containing the resulting environment. Also collects the environment extension state of
+  all environment branches that contributed contained declarations.
+  -/
+  checked             : Task Kernel.Environment := .pure checkedWithoutAsync
+  /--
+  Container of asynchronously elaborated declarations, i.e.
+  `checked = checkedWithoutAsync ⨃ asyncConsts`.
+  -/
+  private asyncConsts : AsyncConsts := {}
+  /-- Information about this asynchronous branch of the environment, if any. -/
+  private asyncCtx?   : Option AsyncContext := none
+deriving Nonempty
+
+namespace Environment
+
+@[export lean_elab_environment_of_kernel_env]
+def ofKernelEnv (env : Kernel.Environment) : Environment :=
+  { checkedWithoutAsync := env }
+
+@[export lean_elab_environment_to_kernel_env]
+def toKernelEnv (env : Environment) : Kernel.Environment :=
+  env.checked.get
+
+/-- Consistently updates synchronous and asynchronous parts of the environment without blocking. -/
+private def modifyCheckedAsync (env : Environment) (f : Kernel.Environment → Kernel.Environment) : Environment :=
+  { env with checked := env.checked.map (sync := true) f, checkedWithoutAsync := f env.checkedWithoutAsync }
+
+/-- Sets synchronous and asynchronous parts of the environment to the given kernel environment. -/
+private def setCheckedSync (env : Environment) (newChecked : Kernel.Environment) : Environment :=
+  { env with checked := .pure newChecked, checkedWithoutAsync := newChecked }
+
+@[extern "lean_elab_add_decl"]
+private opaque addDeclCheck (env : Environment) (maxHeartbeats : USize) (decl : @& Declaration)
+  (cancelTk? : @& Option IO.CancelToken) : Except Kernel.Exception Environment
+
+@[extern "lean_elab_add_decl_without_checking"]
+private opaque addDeclWithoutChecking (env : Environment) (decl : @& Declaration) :
+  Except Kernel.Exception Environment
+
+/--
+Adds given declaration to the environment, type checking it unless `doCheck` is false.
+
+This is a plumbing function for the implementation of `Lean.addDecl`, most users should use it
+instead.
+-/
+def addDeclCore (env : Environment) (maxHeartbeats : USize) (decl : @& Declaration)
+    (cancelTk? : @& Option IO.CancelToken) (doCheck := true) :
+    Except Kernel.Exception Environment := do
+  if let some ctx := env.asyncCtx? then
+    if let some n := decl.getNames.find? (!ctx.mayContain ·) then
+      throw <| .other s!"cannot add declaration {n} to environment as it is restricted to the \
+        prefix {ctx.declPrefix}"
+  if doCheck then
+    addDeclCheck env maxHeartbeats decl cancelTk?
+  else
+    addDeclWithoutChecking env decl
+
+@[inherit_doc Kernel.Environment.constants]
+def constants (env : Environment) : ConstMap :=
+  env.toKernelEnv.constants
+
+@[inherit_doc Kernel.Environment.const2ModIdx]
+def const2ModIdx (env : Environment) : Std.HashMap Name ModuleIdx :=
+  env.toKernelEnv.const2ModIdx
+
+-- only needed for the lakefile.lean cache
+@[export lake_environment_add]
+private def lakeAdd (env : Environment) (cinfo : ConstantInfo) : Environment :=
+  { env with checked := .pure <| env.checked.get.add cinfo }
+
+/--
+Save an extra constant name that is used to populate `const2ModIdx` when we import
+.olean files. We use this feature to save in which module an auxiliary declaration
+created by the code generator has been created.
+-/
+def addExtraName (env : Environment) (name : Name) : Environment :=
+  if env.constants.contains name then
+    env
+  else
+    env.modifyCheckedAsync fun env => { env with extraConstNames := env.extraConstNames.insert name }
+
+/-- Find base case: name did not match any asynchronous declaration. -/
+private def findNoAsync (env : Environment) (n : Name) : Option ConstantInfo := do
+  if env.asyncConsts.hasPrefix n then
+    -- Constant generated in a different environment branch: wait for final kernel environment. Rare
+    -- case when only proofs are elaborated asynchronously as they are rarely inspected. Could be
+    -- optimized in the future by having the elaboration thread publish an (incremental?) map of
+    -- generated declarations before kernel checking (which must wait on all previous threads).
+    env.checked.get.constants.find?' n
+  else
+    -- Not in the kernel environment nor in the name prefix of environment branch: undefined by
+    -- `addDeclCore` invariant.
+    none
+
+/--
+Looks up the given declaration name in the environment, avoiding forcing any in-progress elaboration
+tasks.
+-/
+def findAsync? (env : Environment) (n : Name) : Option AsyncConstantInfo := do
+  -- Check declarations already added to the kernel environment (e.g. because they were imported)
+  -- first as that should be the most common case. It is safe to use `find?'` because we never
+  -- overwrite imported declarations.
+  if let some c := env.checkedWithoutAsync.constants.find?' n then
+    some <| .ofConstantInfo c
+  else if let some asyncConst := env.asyncConsts.find? n then
+    -- Constant for which an asynchronous elaboration task was spawned
+    return asyncConst.constInfo
+  else env.findNoAsync n |>.map .ofConstantInfo
+
+/--
+Looks up the given declaration name in the environment, avoiding forcing any in-progress elaboration
+tasks for declaration bodies (which are not accessible from `ConstantVal`).
+-/
+def findConstVal? (env : Environment) (n : Name) : Option ConstantVal := do
+  if let some c := env.checkedWithoutAsync.constants.find?' n then
+    some c.toConstantVal
+  else if let some asyncConst := env.asyncConsts.find? n then
+    return asyncConst.constInfo.toConstantVal
+  else env.findNoAsync n |>.map (·.toConstantVal)
+
+/--
+Looks up the given declaration name in the environment, blocking on the corresponding elaboration
+task if not yet complete.
+-/
+def find? (env : Environment) (n : Name) : Option ConstantInfo :=
+  if let some c := env.checkedWithoutAsync.constants.find?' n then
+    some c
+  else if let some asyncConst := env.asyncConsts.find? n then
+    return asyncConst.constInfo.toConstantInfo
+  else
+    env.findNoAsync n
+
+/-- Returns debug output about the asynchronous state of the environment. -/
+def dbgFormatAsyncState (env : Environment) : BaseIO String :=
+  return s!"\
+    asyncCtx.declPrefix: {repr <| env.asyncCtx?.map (·.declPrefix)}\
+  \nasyncConsts: {repr <| env.asyncConsts.toArray.map (·.constInfo.name)}\
+  \ncheckedWithoutAsync.constants.map₂: {repr <|
+      env.checkedWithoutAsync.constants.map₂.toList.map (·.1)}"
+
+/-- Returns debug output about the synchronous state of the environment. -/
+def dbgFormatCheckedSyncState (env : Environment) : BaseIO String :=
+  return s!"checked.get.constants.map₂: {repr <| env.checked.get.constants.map₂.toList.map (·.1)}"
+
+/--
+Result of `Lean.Environment.addConstAsync` which is necessary to complete the asynchronous addition.
+-/
+structure AddConstAsyncResult where
+  /--
+  Resulting "main branch" environment which contains the declaration name as an asynchronous
+  constant. Accessing the constant or kernel environment will block until the corresponding
+  `AddConstAsyncResult.commit*` function has been called.
+  -/
+  mainEnv : Environment
+  /--
+  Resulting "async branch" environment which should be used to add the desired declaration in a new
+  task and then call `AddConstAsyncResult.commit*` to commit results back to the main environment.
+  One of `commitCheckEnv` or `commitFailure` must be called eventually to prevent deadlocks on main
+  branch accesses.
+  -/
+  asyncEnv : Environment
+  private constName : Name
+  private kind : ConstantKind
+  private sigPromise : IO.Promise ConstantVal
+  private infoPromise : IO.Promise ConstantInfo
+  private extensionsPromise : IO.Promise (Array EnvExtensionState)
+  private checkedEnvPromise : IO.Promise Kernel.Environment
+
+/--
+Starts the asynchronous addition of a constant to the environment. The environment is split into a
+"main" branch that holds a reference to the constant to be added but will block on access until the
+corresponding information has been added on the "async" environment branch and committed there; see
+the respective fields of `AddConstAsyncResult` as well as the [Environment Branches] note for more
+information.
+-/
+def addConstAsync (env : Environment) (constName : Name) (kind : ConstantKind) (reportExts := true) :
+    IO AddConstAsyncResult := do
+  let sigPromise ← IO.Promise.new
+  let infoPromise ← IO.Promise.new
+  let extensionsPromise ← IO.Promise.new
+  let checkedEnvPromise ← IO.Promise.new
+  let asyncConst := {
+    constInfo := {
+      name := constName
+      kind
+      sig := sigPromise.result
+      constInfo := infoPromise.result
+    }
+    exts? := guard reportExts *> some extensionsPromise.result
+  }
+  return {
+    constName, kind
+    mainEnv := { env with
+      asyncConsts := env.asyncConsts.add asyncConst
+      checked := checkedEnvPromise.result }
+    asyncEnv := { env with
+      asyncCtx? := some { declPrefix := privateToUserName constName.eraseMacroScopes }
+    }
+    sigPromise, infoPromise, extensionsPromise, checkedEnvPromise
+  }
+
+/--
+Commits the signature of the constant to the main environment branch. The declaration name must
+match the name originally given to `addConstAsync`. It is optional to call this function but can
+help in unblocking corresponding accesses to the constant on the main branch.
+-/
+def AddConstAsyncResult.commitSignature (res : AddConstAsyncResult) (sig : ConstantVal) :
+    IO Unit := do
+  if sig.name != res.constName then
+    throw <| .userError s!"AddConstAsyncResult.commitSignature: constant has name {sig.name} but expected {res.constName}"
+  res.sigPromise.resolve sig
+
+/--
+Commits the full constant info to the main environment branch. If `info?` is `none`, it is taken
+from the given environment. The declaration name and kind must match the original values given to
+`addConstAsync`. The signature must match the previous `commitSignature` call, if any.
+-/
+def AddConstAsyncResult.commitConst (res : AddConstAsyncResult) (env : Environment)
+    (info? : Option ConstantInfo := none) :
+    IO Unit := do
+  let info ← match info? <|> env.find? res.constName with
+    | some info => pure info
+    | none =>
+      throw <| .userError s!"AddConstAsyncResult.commitConst: constant {res.constName} not found in async context"
+  res.commitSignature info.toConstantVal
+  let kind' := .ofConstantInfo info
+  if res.kind != kind' then
+    throw <| .userError s!"AddConstAsyncResult.commitConst: constant has kind {repr kind'} but expected {repr res.kind}"
+  let sig := res.sigPromise.result.get
+  if sig.levelParams != info.levelParams then
+    throw <| .userError s!"AddConstAsyncResult.commitConst: constant has level params {info.levelParams} but expected {sig.levelParams}"
+  if sig.type != info.type then
+    throw <| .userError s!"AddConstAsyncResult.commitConst: constant has type {info.type} but expected {sig.type}"
+  res.infoPromise.resolve info
+  res.extensionsPromise.resolve env.checkedWithoutAsync.extensions
+
+/--
+Aborts async addition, filling in missing information with default values/sorries and leaving the
+kernel environment unchanged.
+-/
+def AddConstAsyncResult.commitFailure (res : AddConstAsyncResult) : BaseIO Unit := do
+  let val := if (← IO.hasFinished res.sigPromise.result) then
+    res.sigPromise.result.get
+  else {
+    name := res.constName
+    levelParams := []
+    type := mkApp2 (mkConst ``sorryAx [0]) (mkSort 0) (mkConst ``true)
+  }
+  res.sigPromise.resolve val
+  res.infoPromise.resolve <| match res.kind with
+    | .defn => .defnInfo { val with
+      value := mkApp2 (mkConst ``sorryAx [0]) val.type (mkConst ``true)
+      hints := .abbrev
+      safety := .safe
+    }
+    | .thm  => .thmInfo { val with
+      value := mkApp2 (mkConst ``sorryAx [0]) val.type (mkConst ``true)
+    }
+    | k => panic! s!"AddConstAsyncResult.commitFailure: unsupported constant kind {repr k}"
+  res.extensionsPromise.resolve #[]
+  let _ ← BaseIO.mapTask (t := res.asyncEnv.checked) (sync := true) res.checkedEnvPromise.resolve
+
+/--
+Assuming `Lean.addDecl` has been run for the constant to be added on the async environment branch,
+commits the full constant info from that call to the main environment, waits for the final kernel
+environment resulting from the `addDecl` call, and commits it to the main branch as well, unblocking
+kernel additions there. All `commitConst` preconditions apply.
+-/
+def AddConstAsyncResult.commitCheckEnv (res : AddConstAsyncResult) (env : Environment) :
+    IO Unit := do
+  let some _ := env.findAsync? res.constName
+    | throw <| .userError s!"AddConstAsyncResult.checkAndCommitEnv: constant {res.constName} not \
+      found in async context"
+  res.commitConst env
+  res.checkedEnvPromise.resolve env.checked.get
+
+def contains (env : Environment) (n : Name) : Bool :=
+  env.findAsync? n |>.isSome
+
+def header (env : Environment) : EnvironmentHeader :=
+  -- can be assumed to be in sync with `env.checked`; see `setMainModule`, the only modifier of the header
+  env.checkedWithoutAsync.header
+
+def imports (env : Environment) : Array Import :=
+  env.header.imports
+
+def allImportedModuleNames (env : Environment) : Array Name :=
+  env.header.moduleNames
+
+def setMainModule (env : Environment) (m : Name) : Environment :=
+  env.modifyCheckedAsync ({ · with header.mainModule := m })
+
+def mainModule (env : Environment) : Name :=
+  env.header.mainModule
+
+def getModuleIdxFor? (env : Environment) (declName : Name) : Option ModuleIdx :=
+  -- async constants are always from the current module
+  env.checkedWithoutAsync.const2ModIdx[declName]?
+
+def isConstructor (env : Environment) (declName : Name) : Bool :=
+  match env.find? declName with
+  | some (.ctorInfo _) => true
+  | _                  => false
+
+def isSafeDefinition (env : Environment) (declName : Name) : Bool :=
+  match env.find? declName with
+  | some (.defnInfo { safety := .safe, .. }) => true
+  | _ => false
+
+def getModuleIdx? (env : Environment) (moduleName : Name) : Option ModuleIdx :=
+  env.header.moduleNames.findIdx? (· == moduleName)
 
 end Environment
 
@@ -385,20 +864,22 @@ opaque EnvExtensionInterfaceImp : EnvExtensionInterface
 def EnvExtension (σ : Type) : Type := EnvExtensionInterfaceImp.ext σ
 
 private def ensureExtensionsArraySize (env : Environment) : IO Environment := do
-  let exts ← EnvExtensionInterfaceImp.ensureExtensionsSize env.extensions
-  return { env with extensions := exts }
+  let exts ← EnvExtensionInterfaceImp.ensureExtensionsSize env.checked.get.extensions
+  return env.modifyCheckedAsync ({ · with extensions := exts })
 
 namespace EnvExtension
 instance {σ} [s : Inhabited σ] : Inhabited (EnvExtension σ) := EnvExtensionInterfaceImp.inhabitedExt s
 
 def setState {σ : Type} (ext : EnvExtension σ) (env : Environment) (s : σ) : Environment :=
-  { env with extensions := EnvExtensionInterfaceImp.setState ext env.extensions s }
+  let checked := env.checked.get
+  env.setCheckedSync { checked with extensions := EnvExtensionInterfaceImp.setState ext checked.extensions s }
 
 def modifyState {σ : Type} (ext : EnvExtension σ) (env : Environment) (f : σ → σ) : Environment :=
-  { env with extensions := EnvExtensionInterfaceImp.modifyState ext env.extensions f }
+  let checked := env.checked.get
+  env.setCheckedSync { checked with extensions := EnvExtensionInterfaceImp.modifyState ext checked.extensions f }
 
 def getState {σ : Type} [Inhabited σ] (ext : EnvExtension σ) (env : Environment) : σ :=
-  EnvExtensionInterfaceImp.getState ext env.extensions
+  EnvExtensionInterfaceImp.getState ext env.checked.get.extensions
 
 end EnvExtension
 
@@ -418,11 +899,13 @@ def mkEmptyEnvironment (trustLevel : UInt32 := 0) : IO Environment := do
   if initializing then throw (IO.userError "environment objects cannot be created during initialization")
   let exts ← mkInitialExtensionStates
   pure {
-    const2ModIdx    := {}
-    constants       := {}
-    header          := { trustLevel := trustLevel }
-    extraConstNames := {}
-    extensions      := exts
+    checkedWithoutAsync := {
+      const2ModIdx    := {}
+      constants       := {}
+      header          := { trustLevel }
+      extraConstNames := {}
+      extensions      := exts
+    }
   }
 
 structure PersistentEnvExtensionState (α : Type) (σ : Type) where
@@ -706,11 +1189,12 @@ def mkModuleData (env : Environment) : IO ModuleData := do
   let entries := pExts.map fun pExt =>
     let state := pExt.getState env
     (pExt.name, pExt.exportEntriesFn state)
-  let constNames := env.constants.foldStage2 (fun names name _ => names.push name) #[]
-  let constants  := env.constants.foldStage2 (fun cs _ c => cs.push c) #[]
+  let kenv := env.toKernelEnv
+  let constNames := kenv.constants.foldStage2 (fun names name _ => names.push name) #[]
+  let constants  := kenv.constants.foldStage2 (fun cs _ c => cs.push c) #[]
   return {
     imports         := env.header.imports
-    extraConstNames := env.extraConstNames.toArray
+    extraConstNames := env.checked.get.extraConstNames.toArray
     constNames, constants, entries
   }
 
@@ -731,19 +1215,23 @@ def mkExtNameMap (startingAt : Nat) : IO (Std.HashMap Name Nat) := do
   return result
 
 private def setImportedEntries (env : Environment) (mods : Array ModuleData) (startingAt : Nat := 0) : IO Environment := do
-  let mut env := env
+  -- We work directly on the states array instead of `env` as `Environment.modifyState` introduces
+  -- significant overhead on such frequent calls
+  let mut states := env.checkedWithoutAsync.extensions
   let extDescrs ← persistentEnvExtensionsRef.get
   /- For extensions starting at `startingAt`, ensure their `importedEntries` array have size `mods.size`. -/
   for extDescr in extDescrs[startingAt:] do
-    env := extDescr.toEnvExtension.modifyState env fun s => { s with importedEntries := mkArray mods.size #[] }
+    states := EnvExtensionInterfaceImp.modifyState extDescr.toEnvExtension states fun s =>
+      { s with importedEntries := mkArray mods.size #[] }
   /- For each module `mod`, and `mod.entries`, if the extension name is one of the extensions after `startingAt`, set `entries` -/
   let extNameIdx ← mkExtNameMap startingAt
   for h : modIdx in [:mods.size] do
     let mod := mods[modIdx]
     for (extName, entries) in mod.entries do
       if let some entryIdx := extNameIdx[extName]? then
-        env := extDescrs[entryIdx]!.toEnvExtension.modifyState env fun s => { s with importedEntries := s.importedEntries.set! modIdx entries }
-  return env
+        states := EnvExtensionInterfaceImp.modifyState extDescrs[entryIdx]!.toEnvExtension states fun s =>
+          { s with importedEntries := s.importedEntries.set! modIdx entries }
+  return env.setCheckedSync { env.checkedWithoutAsync with extensions := states }
 
 /--
   "Forward declaration" needed for updating the attribute table with user-defined attributes.
@@ -873,17 +1361,17 @@ def finalizeImport (s : ImportState) (imports : Array Import) (opts : Options) (
   let constants : ConstMap := SMap.fromHashMap constantMap false
   let exts ← mkInitialExtensionStates
   let mut env : Environment := {
-    const2ModIdx    := const2ModIdx
-    constants       := constants
-    extraConstNames := {}
-    extensions      := exts
-    header          := {
-      quotInit     := !imports.isEmpty -- We assume `core.lean` initializes quotient module
-      trustLevel   := trustLevel
-      imports      := imports
-      regions      := s.regions
-      moduleNames  := s.moduleNames
-      moduleData   := s.moduleData
+    checkedWithoutAsync := {
+      const2ModIdx, constants
+      quotInit        := !imports.isEmpty -- We assume `core.lean` initializes quotient module
+      extraConstNames := {}
+      extensions      := exts
+      header     := {
+        trustLevel, imports
+        regions      := s.regions
+        moduleNames  := s.moduleNames
+        moduleData   := s.moduleData
+      }
     }
   }
   env ← setImportedEntries env s.moduleData
@@ -946,54 +1434,21 @@ builtin_initialize namespacesExt : SimplePersistentEnvExtension Name NameSSet
     addEntryFn      := fun s n => s.insert n
   }
 
-structure Kernel.Diagnostics where
-  /-- Number of times each declaration has been unfolded by the kernel. -/
-  unfoldCounter : PHashMap Name Nat := {}
-  /-- If `enabled = true`, kernel records declarations that have been unfolded. -/
-  enabled : Bool := false
-  deriving Inhabited
+@[inherit_doc Kernel.Environment.enableDiag]
+def Kernel.enableDiag (env : Lean.Environment) (flag : Bool) : Lean.Environment :=
+  env.modifyCheckedAsync (·.enableDiag flag)
 
-/--
-Extension for storting diagnostic information.
+def Kernel.isDiagnosticsEnabled (env : Lean.Environment) : Bool :=
+  env.checkedWithoutAsync.isDiagnosticsEnabled
 
-Remark: We store kernel diagnostic information in an environment extension to simplify
-the interface with the kernel implemented in C/C++. Thus, we can only track
-declarations in methods, such as `addDecl`, which return a new environment.
-`Kernel.isDefEq` and `Kernel.whnf` do not update the statistics. We claim
-this is ok since these methods are mainly used for debugging.
--/
-builtin_initialize diagExt : EnvExtension Kernel.Diagnostics ←
-  registerEnvExtension (pure {})
+def Kernel.resetDiag (env : Lean.Environment) : Lean.Environment :=
+  env.modifyCheckedAsync (·.resetDiag)
 
-@[export lean_kernel_diag_is_enabled]
-def Kernel.Diagnostics.isEnabled (d : Diagnostics) : Bool :=
-  d.enabled
+def Kernel.getDiagnostics (env : Lean.Environment) : Diagnostics :=
+  env.checked.get.diagnostics
 
-/-- Enables/disables kernel diagnostics. -/
-def Kernel.enableDiag (env : Environment) (flag : Bool) : Environment :=
-  diagExt.modifyState env fun s => { s with enabled := flag }
-
-def Kernel.isDiagnosticsEnabled (env : Environment) : Bool :=
-  diagExt.getState env |>.enabled
-
-def Kernel.resetDiag (env : Environment) : Environment :=
-  diagExt.modifyState env fun s => { s with unfoldCounter := {} }
-
-@[export lean_kernel_record_unfold]
-def Kernel.Diagnostics.recordUnfold (d : Diagnostics) (declName : Name) : Diagnostics :=
-  if d.enabled then
-    let cNew := if let some c := d.unfoldCounter.find? declName then c + 1 else 1
-    { d with unfoldCounter := d.unfoldCounter.insert declName cNew }
-  else
-    d
-
-@[export lean_kernel_get_diag]
-def Kernel.getDiagnostics (env : Environment) : Diagnostics :=
-  diagExt.getState env
-
-@[export lean_kernel_set_diag]
-def Kernel.setDiagnostics (env : Environment) (diag : Diagnostics) : Environment :=
-  diagExt.setState env diag
+def Kernel.setDiagnostics (env : Lean.Environment) (diag : Diagnostics) : Lean.Environment :=
+  env.modifyCheckedAsync (·.setDiagnostics diag)
 
 namespace Environment
 
@@ -1009,27 +1464,9 @@ def isNamespace (env : Environment) (n : Name) : Bool :=
 def getNamespaceSet (env : Environment) : NameSSet :=
   namespacesExt.getState env
 
-private def isNamespaceName : Name → Bool
-  | .str .anonymous _ => true
-  | .str p _          => isNamespaceName p
-  | _                 => false
-
-private def registerNamePrefixes : Environment → Name → Environment
-  | env, .str p _ => if isNamespaceName p then registerNamePrefixes (registerNamespace env p) p else env
-  | env, _        => env
-
-@[export lean_environment_add]
-private def add (env : Environment) (cinfo : ConstantInfo) : Environment :=
-  let name := cinfo.name
-  let env := match name with
-    | .str _ s =>
-      if s.get 0 == '_' then
-        -- Do not register namespaces that only contain internal declarations.
-        env
-      else
-        registerNamePrefixes env name
-    | _ => env
-  env.addAux cinfo
+@[export lean_elab_environment_update_base_after_kernel_add]
+private def updateBaseAfterKernelAdd (env : Environment) (kernel : Kernel.Environment) : Environment :=
+  env.setCheckedSync kernel
 
 @[export lean_display_stats]
 def displayStats (env : Environment) : IO Unit := do
@@ -1039,7 +1476,7 @@ def displayStats (env : Environment) : IO Unit := do
   IO.println ("number of memory-mapped modules:       " ++ toString (env.header.regions.filter (·.isMemoryMapped) |>.size));
   IO.println ("number of buckets for imported consts: " ++ toString env.constants.numBuckets);
   IO.println ("trust level:                           " ++ toString env.header.trustLevel);
-  IO.println ("number of extensions:                  " ++ toString env.extensions.size);
+  IO.println ("number of extensions:                  " ++ toString env.checkedWithoutAsync.extensions.size);
   pExtDescrs.forM fun extDescr => do
     IO.println ("extension '" ++ toString extDescr.name ++ "'")
     let s := extDescr.toEnvExtension.getState env
@@ -1085,27 +1522,33 @@ namespace Kernel
 
 /--
   Kernel isDefEq predicate. We use it mainly for debugging purposes.
-  Recall that the Kernel type checker does not support metavariables.
+  Recall that the kernel type checker does not support metavariables.
   When implementing automation, consider using the `MetaM` methods. -/
+-- We use `Lean.Environment` for ease of use; as this is a debugging function, we forgo a
+-- `Kernel.Environment` base variant
 @[extern "lean_kernel_is_def_eq"]
-opaque isDefEq (env : Environment) (lctx : LocalContext) (a b : Expr) : Except KernelException Bool
+opaque isDefEq (env : Lean.Environment) (lctx : LocalContext) (a b : Expr) : Except Kernel.Exception Bool
 
-def isDefEqGuarded (env : Environment) (lctx : LocalContext) (a b : Expr) : Bool :=
+def isDefEqGuarded (env : Lean.Environment) (lctx : LocalContext) (a b : Expr) : Bool :=
   if let .ok result := isDefEq env lctx a b then result else false
 
 /--
   Kernel WHNF function. We use it mainly for debugging purposes.
-  Recall that the Kernel type checker does not support metavariables.
+  Recall that the kernel type checker does not support metavariables.
   When implementing automation, consider using the `MetaM` methods. -/
+-- We use `Lean.Environment` for ease of use; as this is a debugging function, we forgo a
+-- `Kernel.Environment` base variant
 @[extern "lean_kernel_whnf"]
-opaque whnf (env : Environment) (lctx : LocalContext) (a : Expr) : Except KernelException Expr
+opaque whnf (env : Lean.Environment) (lctx : LocalContext) (a : Expr) : Except Kernel.Exception Expr
 
 /--
   Kernel typecheck function. We use it mainly for debugging purposes.
   Recall that the Kernel type checker does not support metavariables.
   When implementing automation, consider using the `MetaM` methods. -/
+-- We use `Lean.Environment` for ease of use; as this is a debugging function, we forgo a
+-- `Kernel.Environment` base variant
 @[extern "lean_kernel_check"]
-opaque check (env : Environment) (lctx : LocalContext) (a : Expr) : Except KernelException Expr
+opaque check (env : Lean.Environment) (lctx : LocalContext) (a : Expr) : Except Kernel.Exception Expr
 
 end Kernel
 

src/Lean/Exception.lean

@@ -89,11 +89,11 @@ def ofExcept [Monad m] [MonadError m] [ToMessageData ε] (x : Except ε α) : m
 /--
 Throw an error exception for the given kernel exception.
 -/
-def throwKernelException [Monad m] [MonadError m] [MonadOptions m] (ex : KernelException) : m α := do
+def throwKernelException [Monad m] [MonadError m] [MonadOptions m] (ex : Kernel.Exception) : m α := do
   Lean.throwError <| ex.toMessageData (← getOptions)
 
 /-- Lift from `Except KernelException` to `m` when `m` can throw kernel exceptions. -/
-def ofExceptKernelException [Monad m] [MonadError m] [MonadOptions m] (x : Except KernelException α) : m α :=
+def ofExceptKernelException [Monad m] [MonadError m] [MonadOptions m] (x : Except Kernel.Exception α) : m α :=
   match x with
   | .ok a    => return a
   | .error e => throwKernelException e

src/Lean/Expr.lean

@@ -639,7 +639,7 @@ def mkFVar (fvarId : FVarId) : Expr :=
 /--
 `.mvar mvarId` is now the preferred form.
 This function is seldom used, metavariables are often created using functions such
-as `mkFresheExprMVar` at `MetaM`.
+as `mkFreshExprMVar` at `MetaM`.
 -/
 def mkMVar (mvarId : MVarId) : Expr :=
   .mvar mvarId

src/Lean/Message.lean

@@ -448,6 +448,9 @@ def markAllReported (log : MessageLog) : MessageLog :=
 def errorsToWarnings (log : MessageLog) : MessageLog :=
   { unreported := log.unreported.map (fun m => match m.severity with | MessageSeverity.error => { m with severity := MessageSeverity.warning } | _ => m) }
 
+def errorsToInfos (log : MessageLog) : MessageLog :=
+  { unreported := log.unreported.map (fun m => match m.severity with | MessageSeverity.error => { m with severity := MessageSeverity.information } | _ => m) }
+
 def getInfoMessages (log : MessageLog) : MessageLog :=
   { unreported := log.unreported.filter fun m => match m.severity with | MessageSeverity.information => true | _ => false }
 
@@ -537,12 +540,12 @@ macro_rules
 def toMessageList (msgs : Array MessageData) : MessageData :=
   indentD (MessageData.joinSep msgs.toList m!"\n\n")
 
-namespace KernelException
+namespace Kernel.Exception
 
 private def mkCtx (env : Environment) (lctx : LocalContext) (opts : Options) (msg : MessageData) : MessageData :=
-  MessageData.withContext { env := env, mctx := {}, lctx := lctx, opts := opts } msg
+  MessageData.withContext { env := .ofKernelEnv env, mctx := {}, lctx := lctx, opts := opts } msg
 
-def toMessageData (e : KernelException) (opts : Options) : MessageData :=
+def toMessageData (e : Kernel.Exception) (opts : Options) : MessageData :=
   match e with
   | unknownConstant env constName       => mkCtx env {} opts m!"(kernel) unknown constant '{constName}'"
   | alreadyDeclared env constName       => mkCtx env {} opts m!"(kernel) constant has already been declared '{.ofConstName constName true}'"
@@ -570,5 +573,5 @@ def toMessageData (e : KernelException) (opts : Options) : MessageData :=
   | deepRecursion                       => "(kernel) deep recursion detected"
   | interrupted                         => "(kernel) interrupted"
 
-end KernelException
+end Kernel.Exception
 end Lean

src/Lean/Meta/Constructions/CasesOn.lean

@@ -9,13 +9,13 @@ import Lean.Meta.Basic
 
 namespace Lean
 
-@[extern "lean_mk_cases_on"] opaque mkCasesOnImp (env : Environment) (declName : @& Name) : Except KernelException Declaration
+@[extern "lean_mk_cases_on"] opaque mkCasesOnImp (env : Kernel.Environment) (declName : @& Name) : Except Kernel.Exception Declaration
 
 open Meta
 
 def mkCasesOn (declName : Name) : MetaM Unit := do
   let name := mkCasesOnName declName
-  let decl ← ofExceptKernelException (mkCasesOnImp (← getEnv) declName)
+  let decl ← ofExceptKernelException (mkCasesOnImp (← getEnv).toKernelEnv declName)
   addDecl decl
   setReducibleAttribute name
   modifyEnv fun env => markAuxRecursor env name

src/Lean/Meta/Constructions/NoConfusion.lean

@@ -10,8 +10,8 @@ import Lean.Meta.CompletionName
 
 namespace Lean
 
-@[extern "lean_mk_no_confusion_type"] opaque mkNoConfusionTypeCoreImp (env : Environment) (declName : @& Name) : Except KernelException Declaration
-@[extern "lean_mk_no_confusion"] opaque mkNoConfusionCoreImp (env : Environment) (declName : @& Name) : Except KernelException Declaration
+@[extern "lean_mk_no_confusion_type"] opaque mkNoConfusionTypeCoreImp (env : Environment) (declName : @& Name) : Except Kernel.Exception Declaration
+@[extern "lean_mk_no_confusion"] opaque mkNoConfusionCoreImp (env : Environment) (declName : @& Name) : Except Kernel.Exception Declaration
 
 open Meta
 

src/Lean/Meta/Diagnostics.lean

@@ -72,12 +72,12 @@ def mkDiagSynthPendingFailure (failures : PHashMap Expr MessageData) : MetaM Dia
 /--
 We use below that this returns `m` unchanged if `s.isEmpty`
 -/
-def appendSection (m : MessageData) (cls : Name) (header : String) (s : DiagSummary) (resultSummary := true) : MessageData :=
+def appendSection (m : Array MessageData) (cls : Name) (header : String) (s : DiagSummary) (resultSummary := true) : Array MessageData :=
   if s.isEmpty then
     m
   else
     let header := if resultSummary then s!"{header} (max: {s.max}, num: {s.data.size}):" else header
-    m ++ .trace { cls } header s.data
+    m.push <| .trace { cls } header s.data
 
 def reportDiag : MetaM Unit := do
   if (← isDiagnosticsEnabled) then
@@ -89,7 +89,7 @@ def reportDiag : MetaM Unit := do
     let inst ← mkDiagSummaryForUsedInstances
     let synthPending ← mkDiagSynthPendingFailure (← get).diag.synthPendingFailures
     let unfoldKernel ← mkDiagSummary `kernel (Kernel.getDiagnostics (← getEnv)).unfoldCounter
-    let m := MessageData.nil
+    let m := #[]
     let m := appendSection m `reduction "unfolded declarations" unfoldDefault
     let m := appendSection m `reduction "unfolded instances" unfoldInstance
     let m := appendSection m `reduction "unfolded reducible declarations" unfoldReducible
@@ -99,8 +99,8 @@ def reportDiag : MetaM Unit := do
               synthPending (resultSummary := false)
     let m := appendSection m `def_eq "heuristic for solving `f a =?= f b`" heu
     let m := appendSection m `kernel "unfolded declarations" unfoldKernel
-    unless m matches .nil do
-      let m := m ++ "use `set_option diagnostics.threshold <num>` to control threshold for reporting counters"
-      logInfo m
+    unless m.isEmpty do
+      let m := m.push "use `set_option diagnostics.threshold <num>` to control threshold for reporting counters"
+      logInfo <| .trace { cls := `diag, collapsed := false } "Diagnostics" m
 
 end Lean.Meta

src/Lean/Meta/ExprDefEq.lean

@@ -1233,10 +1233,7 @@ private def processAssignment' (mvarApp : Expr) (v : Expr) : MetaM Bool := do
 
 private def isDeltaCandidate? (t : Expr) : MetaM (Option ConstantInfo) := do
   match t.getAppFn with
-  | .const c _ =>
-    match (← getUnfoldableConst? c) with
-    | r@(some info) => if info.hasValue then return r else return none
-    | _             => return none
+  | .const c _ => getUnfoldableConst? c
   | _ => pure none
 
 /-- Auxiliary method for isDefEqDelta -/

src/Lean/Meta/GetUnfoldableConst.lean

@@ -30,7 +30,7 @@ def canUnfold (info : ConstantInfo) : MetaM Bool := do
 
 /--
 Look up a constant name, returning the `ConstantInfo`
-if it should be unfolded at the current reducibility settings,
+if it is a def/theorem that should be unfolded at the current reducibility settings,
 or `none` otherwise.
 
 This is part of the implementation of `whnf`.
@@ -40,7 +40,7 @@ def getUnfoldableConst? (constName : Name) : MetaM (Option ConstantInfo) := do
   match (← getEnv).find? constName with
   | some (info@(.thmInfo _))  => getTheoremInfo info
   | some (info@(.defnInfo _)) => if (← canUnfold info) then return info else return none
-  | some info                 => return some info
+  | some _                    => return none
   | none                      => throwUnknownConstant constName
 
 /--
@@ -50,7 +50,6 @@ def getUnfoldableConstNoEx? (constName : Name) : MetaM (Option ConstantInfo) :=
   match (← getEnv).find? constName with
   | some (info@(.thmInfo _))  => getTheoremInfo info
   | some (info@(.defnInfo _)) => if (← canUnfold info) then return info else return none
-  | some info                 => return some info
-  | none                      => return none
+  | _                         => return none
 
 end Meta

src/Lean/Meta/IndPredBelow.lean

@@ -296,7 +296,7 @@ where
     m.apply recursor
 
   applyCtors (ms : List MVarId) : MetaM $ List MVarId := do
-    let mss ← ms.toArray.mapIdxM fun _ m => do
+    let mss ← ms.toArray.mapM fun m => do
       let m ← introNPRec m
       (← m.getType).withApp fun below args =>
       m.withContext do

src/Lean/Meta/Tactic.lean

@@ -41,3 +41,4 @@ import Lean.Meta.Tactic.FunInd
 import Lean.Meta.Tactic.Rfl
 import Lean.Meta.Tactic.Rewrites
 import Lean.Meta.Tactic.Grind
+import Lean.Meta.Tactic.Ext

src/Lean/Meta/Tactic/Ext.lean

@@ -0,0 +1,76 @@
+/-
+Copyright (c) 2021 Gabriel Ebner. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Gabriel Ebner, Mario Carneiro
+-/
+prelude
+import Init.Data.Array.InsertionSort
+import Lean.Meta.DiscrTree
+
+namespace Lean.Meta.Ext
+
+/-!
+### Environment extension for `ext` theorems
+-/
+
+/-- Information about an extensionality theorem, stored in the environment extension. -/
+structure ExtTheorem where
+  /-- Declaration name of the extensionality theorem. -/
+  declName : Name
+  /-- Priority of the extensionality theorem. -/
+  priority : Nat
+  /--
+  Key in the discrimination tree,
+  for the type in which the extensionality theorem holds.
+  -/
+  keys : Array DiscrTree.Key
+  deriving Inhabited, Repr, BEq, Hashable
+
+/-- The state of the `ext` extension environment -/
+structure ExtTheorems where
+  /-- The tree of `ext` extensions. -/
+  tree   : DiscrTree ExtTheorem := {}
+  /-- Erased `ext`s via `attribute [-ext]`. -/
+  erased  : PHashSet Name := {}
+  deriving Inhabited
+
+/-- The environment extension to track `@[ext]` theorems. -/
+builtin_initialize extExtension :
+    SimpleScopedEnvExtension ExtTheorem ExtTheorems ←
+  registerSimpleScopedEnvExtension {
+    addEntry := fun { tree, erased } thm =>
+      { tree := tree.insertCore thm.keys thm, erased := erased.erase thm.declName }
+    initial := {}
+  }
+
+/-- Gets the list of `@[ext]` theorems corresponding to the key `ty`,
+ordered from high priority to low. -/
+@[inline] def getExtTheorems (ty : Expr) : MetaM (Array ExtTheorem) := do
+  let extTheorems := extExtension.getState (← getEnv)
+  let arr ← extTheorems.tree.getMatch ty
+  let erasedArr := arr.filter fun thm => !extTheorems.erased.contains thm.declName
+  -- Using insertion sort because it is stable and the list of matches should be mostly sorted.
+  -- Most ext theorems have default priority.
+  return erasedArr.insertionSort (·.priority < ·.priority) |>.reverse
+
+/--
+Erases a name marked `ext` by adding it to the state's `erased` field and
+removing it from the state's list of `Entry`s.
+
+This is triggered by `attribute [-ext] name`.
+-/
+def ExtTheorems.eraseCore (d : ExtTheorems) (declName : Name) : ExtTheorems :=
+ { d with erased := d.erased.insert declName }
+
+/--
+Erases a name marked as a `ext` attribute.
+Check that it does in fact have the `ext` attribute by making sure it names a `ExtTheorem`
+found somewhere in the state's tree, and is not erased.
+-/
+def ExtTheorems.erase [Monad m] [MonadError m] (d : ExtTheorems) (declName : Name) :
+    m ExtTheorems := do
+  unless d.tree.containsValueP (·.declName == declName) && !d.erased.contains declName do
+    throwError "'{declName}' does not have [ext] attribute"
+  return d.eraseCore declName
+
+end Lean.Meta.Ext

src/Lean/Meta/Tactic/Grind.lean

@@ -25,6 +25,7 @@ import Lean.Meta.Tactic.Grind.EMatch
 import Lean.Meta.Tactic.Grind.Main
 import Lean.Meta.Tactic.Grind.CasesMatch
 import Lean.Meta.Tactic.Grind.Arith
+import Lean.Meta.Tactic.Grind.Ext
 
 namespace Lean
 
@@ -38,6 +39,7 @@ builtin_initialize registerTraceClass `grind.ematch.pattern
 builtin_initialize registerTraceClass `grind.ematch.pattern.search
 builtin_initialize registerTraceClass `grind.ematch.instance
 builtin_initialize registerTraceClass `grind.ematch.instance.assignment
+builtin_initialize registerTraceClass `grind.eqResolution
 builtin_initialize registerTraceClass `grind.issues
 builtin_initialize registerTraceClass `grind.simp
 builtin_initialize registerTraceClass `grind.split
@@ -51,6 +53,7 @@ builtin_initialize registerTraceClass `grind.offset.propagate
 builtin_initialize registerTraceClass `grind.offset.eq
 builtin_initialize registerTraceClass `grind.offset.eq.to (inherited := true)
 builtin_initialize registerTraceClass `grind.offset.eq.from (inherited := true)
+builtin_initialize registerTraceClass `grind.beta
 
 /-! Trace options for `grind` developers -/
 builtin_initialize registerTraceClass `grind.debug
@@ -65,4 +68,7 @@ builtin_initialize registerTraceClass `grind.debug.split
 builtin_initialize registerTraceClass `grind.debug.canon
 builtin_initialize registerTraceClass `grind.debug.offset
 builtin_initialize registerTraceClass `grind.debug.offset.proof
+builtin_initialize registerTraceClass `grind.debug.ematch.pattern
+builtin_initialize registerTraceClass `grind.debug.beta
+
 end Lean

src/Lean/Meta/Tactic/Grind/Attr.lean

@@ -10,12 +10,6 @@ import Lean.Meta.Tactic.Simp.Simproc
 namespace Lean.Meta.Grind
 open Simp
 
-builtin_initialize grindNormExt : SimpExtension ←
-  registerSimpAttr `grind_norm "simplification/normalization theorems for `grind`"
-
-builtin_initialize grindNormSimprocExt : SimprocExtension ←
-  registerSimprocAttr `grind_norm_proc "simplification/normalization procedured for `grind`" none
-
 builtin_initialize grindCasesExt : SimpleScopedEnvExtension Name NameSet ←
   registerSimpleScopedEnvExtension {
     initial        := {}

src/Lean/Meta/Tactic/Grind/Beta.lean

@@ -0,0 +1,77 @@
+/-
+Copyright (c) 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Lean.Meta.Tactic.Grind.Types
+
+namespace Lean.Meta.Grind
+
+/-- Returns all lambda expressions in the equivalence class with root `root`. -/
+def getEqcLambdas (root : ENode) : GoalM (Array Expr) := do
+  unless root.hasLambdas do return #[]
+  foldEqc root.self (init := #[]) fun n lams =>
+    if n.self.isLambda then return lams.push n.self else return lams
+
+/--
+Returns the root of the functions in the equivalence class containing `e`.
+That is, if `f a` is in `root`s equivalence class, results contains the root of `f`.
+-/
+def getFnRoots (e : Expr) : GoalM (Array Expr) := do
+  foldEqc e (init := #[]) fun n fns => do
+    let fn := n.self.getAppFn
+    let fnRoot := (← getRoot? fn).getD fn
+    if Option.isNone <| fns.find? (isSameExpr · fnRoot) then
+      return fns.push fnRoot
+    else
+      return fns
+
+/--
+For each `lam` in `lams` s.t. `lam` and `f` are in the same equivalence class,
+propagate `f args = lam args`.
+-/
+def propagateBetaEqs (lams : Array Expr) (f : Expr) (args : Array Expr) : GoalM Unit := do
+  if args.isEmpty then return ()
+  for lam in lams do
+    let rhs := lam.beta args
+    unless rhs.isLambda do
+      let mut gen := Nat.max (← getGeneration lam) (← getGeneration f)
+      let lhs := mkAppN f args
+      if (← hasSameType f lam) then
+        let mut h ← mkEqProof f lam
+        for arg in args do
+          gen := Nat.max gen (← getGeneration arg)
+          h ← mkCongrFun h arg
+        let eq ← mkEq lhs rhs
+        trace[grind.beta] "{eq}, using {lam}"
+        addNewFact h eq (gen+1)
+
+private def isPropagateBetaTarget (e : Expr) : GoalM Bool := do
+  let .app f _ := e | return false
+  go f
+where
+  go (f : Expr) : GoalM Bool := do
+    if let some root ← getRootENode? f then
+      return root.hasLambdas
+    let .app f _ := f | return false
+    go f
+
+/--
+Applies beta-reduction for lambdas in `f`s equivalence class.
+We use this function while internalizing new applications.
+-/
+def propagateBetaForNewApp (e : Expr) : GoalM Unit := do
+  unless (← isPropagateBetaTarget e) do return ()
+  let mut e := e
+  let mut args := #[]
+  repeat
+    unless args.isEmpty do
+      if let some root ← getRootENode? e then
+        if root.hasLambdas then
+          propagateBetaEqs (← getEqcLambdas root) e args.reverse
+    let .app f arg := e | return ()
+    e := f
+    args := args.push arg
+
+end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/Core.lean

@@ -11,6 +11,7 @@ import Lean.Meta.Tactic.Grind.Inv
 import Lean.Meta.Tactic.Grind.PP
 import Lean.Meta.Tactic.Grind.Ctor
 import Lean.Meta.Tactic.Grind.Util
+import Lean.Meta.Tactic.Grind.Beta
 import Lean.Meta.Tactic.Grind.Internalize
 
 namespace Lean.Meta.Grind
@@ -40,7 +41,7 @@ Remove `root` parents from the congruence table.
 This is an auxiliary function performed while merging equivalence classes.
 -/
 private def removeParents (root : Expr) : GoalM ParentSet := do
-  let parents ← getParentsAndReset root
+  let parents ← getParents root
   for parent in parents do
     -- Recall that we may have `Expr.forallE` in `parents` because of `ForallProp.lean`
     if (← pure parent.isApp <&&> isCongrRoot parent) then
@@ -107,6 +108,31 @@ private def propagateOffsetEq (rhsRoot lhsRoot : ENode) : GoalM Unit := do
     if let some rhsOffset := rhsRoot.offset? then
       Arith.processNewOffsetEqLit rhsOffset lhsRoot.self
 
+/--
+Tries to apply beta-reductiong using the parent applications of the functions in `fns` with
+the lambda expressions in `lams`.
+-/
+def propagateBeta (lams : Array Expr) (fns : Array Expr) : GoalM Unit := do
+  if lams.isEmpty then return ()
+  let lamRoot ← getRoot lams.back!
+  trace[grind.debug.beta] "fns: {fns}, lams: {lams}"
+  for fn in fns do
+    trace[grind.debug.beta] "fn: {fn}, parents: {(← getParents fn).toArray}"
+    for parent in (← getParents fn) do
+      let mut args := #[]
+      let mut curr := parent
+      trace[grind.debug.beta] "parent: {parent}"
+      repeat
+        trace[grind.debug.beta] "curr: {curr}"
+        if (← isEqv curr lamRoot) then
+          propagateBetaEqs lams curr args.reverse
+        let .app f arg := curr
+          | break
+        -- Remark: recall that we do not eagerly internalize partial applications.
+        internalize curr (← getGeneration parent)
+        args := args.push arg
+        curr := f
+
 private partial def addEqStep (lhs rhs proof : Expr) (isHEq : Bool) : GoalM Unit := do
   let lhsNode ← getENode lhs
   let rhsNode ← getENode rhs
@@ -158,6 +184,10 @@ where
       proof?  := proof
       flipped
     }
+    let lams₁ ← getEqcLambdas lhsRoot
+    let lams₂ ← getEqcLambdas rhsRoot
+    let fns₁  ← if lams₁.isEmpty then pure #[] else getFnRoots rhsRoot.self
+    let fns₂  ← if lams₂.isEmpty then pure #[] else getFnRoots lhsRoot.self
     let parents ← removeParents lhsRoot.self
     updateRoots lhs rhsNode.root
     trace_goal[grind.debug] "{← ppENodeRef lhs} new root {← ppENodeRef rhsNode.root}, {← ppENodeRef (← getRoot lhs)}"
@@ -172,6 +202,9 @@ where
       hasLambdas := rhsRoot.hasLambdas || lhsRoot.hasLambdas
       heqProofs  := isHEq || rhsRoot.heqProofs || lhsRoot.heqProofs
     }
+    propagateBeta lams₁ fns₁
+    propagateBeta lams₂ fns₂
+    resetParentsOf lhsRoot.self
     copyParentsTo parents rhsNode.root
     unless (← isInconsistent) do
       updateMT rhsRoot.self

src/Lean/Meta/Tactic/Grind/EMatch.lean

@@ -266,7 +266,7 @@ private partial def instantiateTheorem (c : Choice) : M Unit := withDefault do w
   for mvar in mvars, bi in bis do
     if bi.isInstImplicit && !(← mvar.mvarId!.isAssigned) then
       let type ← inferType mvar
-      unless (← synthesizeInstance mvar type) do
+      unless (← synthesizeInstanceAndAssign mvar type) do
         reportIssue m!"failed to synthesize instance when instantiating {← thm.origin.pp}{indentExpr type}"
         return ()
   let proof := mkAppN proof mvars
@@ -278,10 +278,6 @@ private partial def instantiateTheorem (c : Choice) : M Unit := withDefault do w
       reportIssue m!"failed to instantiate {← thm.origin.pp}, failed to instantiate non propositional argument with type{indentExpr (← inferType mvarBad)}"
     let proof ← mkLambdaFVars (binderInfoForMVars := .default) mvars (← instantiateMVars proof)
     addNewInstance thm.origin proof c.gen
-where
-  synthesizeInstance (x type : Expr) : MetaM Bool := do
-    let .some val ← trySynthInstance type | return false
-    isDefEq x val
 
 /-- Process choice stack until we don't have more choices to be processed. -/
 private def processChoices : M Unit := do

src/Lean/Meta/Tactic/Grind/EMatchTheorem.lean

@@ -516,7 +516,9 @@ def mkEMatchEqTheoremCore (origin : Origin) (levelParams : Array Name) (proof :
       | HEq _ lhs _ rhs => pure (lhs, rhs)
       | _ => throwError "invalid E-matching equality theorem, conclusion must be an equality{indentExpr type}"
     let pat := if useLhs then lhs else rhs
+    trace[grind.debug.ematch.pattern] "mkEMatchEqTheoremCore: origin: {← origin.pp}, pat: {pat}, useLhs: {useLhs}"
     let pat ← preprocessPattern pat normalizePattern
+    trace[grind.debug.ematch.pattern] "mkEMatchEqTheoremCore: after preprocessing: {pat}, {← normalize pat}"
     let pats := splitWhileForbidden (pat.abstract xs)
     return (xs.size, pats)
   mkEMatchTheoremCore origin levelParams numParams proof patterns
@@ -551,7 +553,7 @@ def getEMatchTheorems : CoreM EMatchTheorems :=
 
 inductive TheoremKind where
   | eqLhs | eqRhs | eqBoth | fwd | bwd | default
-  deriving Inhabited, BEq
+  deriving Inhabited, BEq, Repr
 
 private def TheoremKind.toAttribute : TheoremKind → String
   | .eqLhs   => "[grind =]"
@@ -651,9 +653,9 @@ private def collectPatterns? (proof : Expr) (xs : Array Expr) (searchPlaces : Ar
 
 def mkEMatchTheoremWithKind? (origin : Origin) (levelParams : Array Name) (proof : Expr) (kind : TheoremKind) : MetaM (Option EMatchTheorem) := do
   if kind == .eqLhs then
-    return (← mkEMatchEqTheoremCore origin levelParams proof (normalizePattern := false) (useLhs := true))
+    return (← mkEMatchEqTheoremCore origin levelParams proof (normalizePattern := true) (useLhs := true))
   else if kind == .eqRhs then
-    return (← mkEMatchEqTheoremCore origin levelParams proof (normalizePattern := false) (useLhs := false))
+    return (← mkEMatchEqTheoremCore origin levelParams proof (normalizePattern := true) (useLhs := false))
   let type ← inferType proof
   forallTelescopeReducing type fun xs type => do
     let searchPlaces ← match kind with
@@ -677,28 +679,40 @@ where
       levelParams, origin
     }
 
-private def getKind (stx : Syntax) : TheoremKind :=
+/-- Return theorem kind for `stx` of the form `Attr.grindThmMod` -/
+def getTheoremKindCore (stx : Syntax) : CoreM TheoremKind := do
+  match stx with
+  | `(Parser.Attr.grindThmMod| =) => return .eqLhs
+  | `(Parser.Attr.grindThmMod| →) => return .fwd
+  | `(Parser.Attr.grindThmMod| ←) => return .bwd
+  | `(Parser.Attr.grindThmMod| =_) => return .eqRhs
+  | `(Parser.Attr.grindThmMod| _=_) => return .eqBoth
+  | _ => throwError "unexpected `grind` theorem kind: `{stx}`"
+
+/-- Return theorem kind for `stx` of the form `(Attr.grindThmMod)?` -/
+def getTheoremKindFromOpt (stx : Syntax) : CoreM TheoremKind := do
   if stx[1].isNone then
-    .default
-  else if stx[1][0].getKind == ``Parser.Attr.grindEq then
-    .eqLhs
-  else if stx[1][0].getKind == ``Parser.Attr.grindFwd then
-    .fwd
-  else if stx[1][0].getKind == ``Parser.Attr.grindEqRhs then
-    .eqRhs
-  else if stx[1][0].getKind == ``Parser.Attr.grindEqBoth then
-    .eqBoth
+    return .default
   else
-    .bwd
+    getTheoremKindCore stx[1][0]
+
+def mkEMatchTheoremForDecl (declName : Name) (thmKind : TheoremKind) : MetaM EMatchTheorem := do
+  let some thm ← mkEMatchTheoremWithKind? (.decl declName) #[] (← getProofFor declName) thmKind
+    | throwError "`@{thmKind.toAttribute} theorem {declName}` {thmKind.explainFailure}, consider using different options or the `grind_pattern` command"
+  return thm
+
+def mkEMatchEqTheoremsForDef? (declName : Name) : MetaM (Option (Array EMatchTheorem)) := do
+  let some eqns ← getEqnsFor? declName | return none
+  eqns.mapM fun eqn => do
+    mkEMatchEqTheorem eqn (normalizePattern := true)
 
 private def addGrindEqAttr (declName : Name) (attrKind : AttributeKind) (thmKind : TheoremKind) (useLhs := true) : MetaM Unit := do
   if (← getConstInfo declName).isTheorem then
     ematchTheoremsExt.add (← mkEMatchEqTheorem declName (normalizePattern := true) (useLhs := useLhs)) attrKind
-  else if let some eqns ← getEqnsFor? declName then
+  else if let some thms ← mkEMatchEqTheoremsForDef? declName then
     unless useLhs do
       throwError "`{declName}` is a definition, you must only use the left-hand side for extracting patterns"
-    for eqn in eqns do
-      ematchTheoremsExt.add (← mkEMatchEqTheorem eqn) attrKind
+    thms.forM (ematchTheoremsExt.add · attrKind)
   else
     throwError s!"`{thmKind.toAttribute}` attribute can only be applied to equational theorems or function definitions"
 
@@ -713,10 +727,26 @@ private def addGrindAttr (declName : Name) (attrKind : AttributeKind) (thmKind :
   else if !(← getConstInfo declName).isTheorem then
     addGrindEqAttr declName attrKind thmKind
   else
-    let some thm ← mkEMatchTheoremWithKind? (.decl declName) #[] (← getProofFor declName) thmKind
-      | throwError "`@{thmKind.toAttribute} theorem {declName}` {thmKind.explainFailure}, consider using different options or the `grind_pattern` command"
+    let thm ← mkEMatchTheoremForDecl declName thmKind
     ematchTheoremsExt.add thm attrKind
 
+def EMatchTheorems.eraseDecl (s : EMatchTheorems) (declName : Name) : MetaM EMatchTheorems := do
+  let throwErr {α} : MetaM α :=
+    throwError "`{declName}` is not marked with the `[grind]` attribute"
+  let info ← getConstInfo declName
+  if !info.isTheorem then
+    if let some eqns ← getEqnsFor? declName then
+       let s := ematchTheoremsExt.getState (← getEnv)
+       unless eqns.all fun eqn => s.contains (.decl eqn) do
+         throwErr
+       return eqns.foldl (init := s) fun s eqn => s.erase (.decl eqn)
+    else
+      throwErr
+  else
+    unless ematchTheoremsExt.getState (← getEnv) |>.contains (.decl declName) do
+      throwErr
+    return s.erase <| .decl declName
+
 builtin_initialize
   registerBuiltinAttribute {
     name := `grind
@@ -739,7 +769,7 @@ builtin_initialize
       `grind` will add an instance of this theorem to the local context whenever it encounters the pattern `foo (foo x)`."
     applicationTime := .afterCompilation
     add := fun declName stx attrKind => do
-      addGrindAttr declName attrKind (getKind stx) |>.run' {}
+      addGrindAttr declName attrKind (← getTheoremKindFromOpt stx) |>.run' {}
     erase := fun declName => MetaM.run' do
       /-
       Remark: consider the following example
@@ -755,21 +785,9 @@ builtin_initialize
       attribute [-grind] foo  -- ok
       ```
       -/
-      let throwErr := throwError "`{declName}` is not marked with the `[grind]` attribute"
-      let info ← getConstInfo declName
-      if !info.isTheorem then
-        if let some eqns ← getEqnsFor? declName then
-           let s := ematchTheoremsExt.getState (← getEnv)
-           unless eqns.all fun eqn => s.contains (.decl eqn) do
-             throwErr
-           modifyEnv fun env => ematchTheoremsExt.modifyState env fun s =>
-             eqns.foldl (init := s) fun s eqn => s.erase (.decl eqn)
-        else
-          throwErr
-      else
-        unless ematchTheoremsExt.getState (← getEnv) |>.contains (.decl declName) do
-          throwErr
-        modifyEnv fun env => ematchTheoremsExt.modifyState env fun s => s.erase (.decl declName)
+      let s := ematchTheoremsExt.getState (← getEnv)
+      let s ← s.eraseDecl declName
+      modifyEnv fun env => ematchTheoremsExt.modifyState env fun _ => s
   }
 
 end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/EqResolution.lean

@@ -0,0 +1,47 @@
+/-
+Copyright (c) 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Lean.Meta.AppBuilder
+
+namespace Lean.Meta.Grind
+/-! A basic "equality resolution" procedure. -/
+
+private def eqResCore (prop proof : Expr) : MetaM (Option (Expr × Expr)) := withNewMCtxDepth do
+  let (ms, _, type) ← forallMetaTelescopeReducing prop
+  if ms.isEmpty then return none
+  let mut progress := false
+  for m in ms do
+    let type ← inferType m
+    let_expr Eq _ lhs rhs ← type
+      | pure ()
+    if (← isDefEq lhs rhs) then
+      unless (← m.mvarId!.checkedAssign (← mkEqRefl lhs)) do
+        return none
+      progress := true
+  unless progress do
+    return none
+  if (← ms.anyM fun m => m.mvarId!.isDelayedAssigned) then
+    return none
+  let prop' ← instantiateMVars type
+  let proof' ← instantiateMVars (mkAppN proof ms)
+  let ms ← ms.filterM fun m => return !(← m.mvarId!.isAssigned)
+  let prop' ← mkForallFVars ms prop' (binderInfoForMVars := .default)
+  let proof' ← mkLambdaFVars ms proof'
+  return some (prop', proof')
+
+/--
+A basic "equality resolution" procedure: Given a proposition `prop` with a proof `proof`, it attempts to resolve equality hypotheses using `isDefEq`. For example, it reduces `∀ x y, f x = f (g y y) → g x y = y` to `∀ y, g (g y y) y = y`, and `∀ (x : Nat), f x ≠ f a` to `False`.
+If successful, the result is a pair `(prop', proof)`, where `prop'` is the simplified proposition,
+and `proof : prop → prop'`
+-/
+def eqResolution (prop : Expr) : MetaM (Option (Expr × Expr)) :=
+  withLocalDeclD `h prop fun h => do
+    let some (prop', proof') ← eqResCore prop h
+      | return none
+    let proof' ← mkLambdaFVars #[h] proof'
+    return some (prop', proof')
+
+end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/Ext.lean

@@ -0,0 +1,40 @@
+/-
+Copyright (c) 2025 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Lean.Meta.Tactic.Grind.Types
+
+namespace Lean.Meta.Grind
+/-! Extensionality theorems support. -/
+
+def instantiateExtTheorem (thm : Ext.ExtTheorem) (e : Expr) : GoalM Unit := withNewMCtxDepth do
+  unless (← getGeneration e) < (← getMaxGeneration) do return ()
+  let c ← mkConstWithFreshMVarLevels thm.declName
+  let (mvars, bis, type) ← withDefault <| forallMetaTelescopeReducing (← inferType c)
+  unless (← isDefEq e type) do
+    reportIssue m!"failed to apply extensionality theorem `{thm.declName}` for {indentExpr e}\nis not definitionally equal to{indentExpr type}"
+    return ()
+  -- Instantiate type class instances
+  for mvar in mvars, bi in bis do
+    if bi.isInstImplicit && !(← mvar.mvarId!.isAssigned) then
+      let type ← inferType mvar
+      unless (← synthesizeInstanceAndAssign mvar type) do
+        reportIssue m!"failed to synthesize instance when instantiating extensionality theorem `{thm.declName}` for {indentExpr e}"
+        return ()
+  -- Remark: `proof c mvars` has type `e`
+  let proof ← instantiateMVars (mkAppN c mvars)
+  -- `e` is equal to `False`
+  let eEqFalse ← mkEqFalseProof e
+  -- So, we use `Eq.mp` to build a `proof` of `False`
+  let proof ← mkEqMP eEqFalse proof
+  let mvars ← mvars.filterM fun mvar => return !(← mvar.mvarId!.isAssigned)
+  let proof' ← instantiateMVars (← mkLambdaFVars mvars proof)
+  let prop' ← inferType proof'
+  if proof'.hasMVar || prop'.hasMVar then
+    reportIssue m!"failed to apply extensionality theorem `{thm.declName}` for {indentExpr e}\nresulting terms contain metavariables"
+    return ()
+  addNewFact proof' prop' ((← getGeneration e) + 1)
+
+end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/ForallProp.lean

@@ -8,6 +8,7 @@ import Init.Grind.Lemmas
 import Lean.Meta.Tactic.Grind.Types
 import Lean.Meta.Tactic.Grind.Internalize
 import Lean.Meta.Tactic.Grind.Simp
+import Lean.Meta.Tactic.Grind.EqResolution
 
 namespace Lean.Meta.Grind
 /--
@@ -96,7 +97,13 @@ def propagateForallPropDown (e : Expr) : GoalM Unit := do
       pushEqTrue a <| mkApp3 (mkConst ``Grind.eq_true_of_imp_eq_false) a b h
       pushEqFalse b <| mkApp3 (mkConst ``Grind.eq_false_of_imp_eq_false) a b h
   else if (← isEqTrue e) then
-    if b.hasLooseBVars then
-      addLocalEMatchTheorems e
+    if let some (e', h') ← eqResolution e then
+      trace[grind.eqResolution] "{e}, {e'}"
+      let h := mkOfEqTrueCore e (← mkEqTrueProof e)
+      let h' := mkApp h' h
+      addNewFact h' e' (← getGeneration e)
+    else
+      if b.hasLooseBVars then
+        addLocalEMatchTheorems e
 
 end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/Internalize.lean

@@ -12,6 +12,7 @@ import Lean.Meta.Match.MatchEqsExt
 import Lean.Meta.Tactic.Grind.Types
 import Lean.Meta.Tactic.Grind.Util
 import Lean.Meta.Tactic.Grind.Canon
+import Lean.Meta.Tactic.Grind.Beta
 import Lean.Meta.Tactic.Grind.Arith.Internalize
 
 namespace Lean.Meta.Grind
@@ -194,7 +195,7 @@ partial def internalize (e : Expr) (generation : Nat) (parent? : Option Expr :=
           activateTheoremPatterns fName generation
         else
           internalize f generation e
-          registerParent e f
+        registerParent e f
         for h : i in [: args.size] do
           let arg := args[i]
           internalize arg generation e
@@ -204,6 +205,8 @@ partial def internalize (e : Expr) (generation : Nat) (parent? : Option Expr :=
       updateAppMap e
       Arith.internalize e parent?
       propagateUp e
+      propagateBetaForNewApp e
+
 end
 
 end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/Main.lean

@@ -20,6 +20,19 @@ import Lean.Meta.Tactic.Grind.SimpUtil
 
 namespace Lean.Meta.Grind
 
+structure Params where
+  config    : Grind.Config
+  ematch    : EMatchTheorems := {}
+  extra     : PArray EMatchTheorem := {}
+  norm      : Simp.Context
+  normProcs : Array Simprocs
+  -- TODO: inductives to split
+
+def mkParams (config : Grind.Config) : MetaM Params := do
+  let norm ← Grind.getSimpContext
+  let normProcs ← Grind.getSimprocs
+  return { config, norm, normProcs }
+
 def mkMethods (fallback : Fallback) : CoreM Methods := do
   let builtinPropagators ← builtinPropagatorsRef.get
   return {
@@ -37,26 +50,29 @@ def mkMethods (fallback : Fallback) : CoreM Methods := do
        prop e
   }
 
-def GrindM.run (x : GrindM α) (mainDeclName : Name) (config : Grind.Config) (fallback : Fallback) : MetaM α := do
+def GrindM.run (x : GrindM α) (mainDeclName : Name) (params : Params) (fallback : Fallback) : MetaM α := do
   let scState := ShareCommon.State.mk _
   let (falseExpr, scState) := ShareCommon.State.shareCommon scState (mkConst ``False)
   let (trueExpr, scState)  := ShareCommon.State.shareCommon scState (mkConst ``True)
   let (natZExpr, scState)  := ShareCommon.State.shareCommon scState (mkNatLit 0)
-  let simprocs ← Grind.getSimprocs
-  let simp ← Grind.getSimpContext
+  let simprocs := params.normProcs
+  let simp := params.norm
+  let config := params.config
   x (← mkMethods fallback).toMethodsRef { mainDeclName, config, simprocs, simp } |>.run' { scState, trueExpr, falseExpr, natZExpr }
 
-private def mkGoal (mvarId : MVarId) : GrindM Goal := do
+private def mkGoal (mvarId : MVarId) (params : Params) : GrindM Goal := do
   let trueExpr ← getTrueExpr
   let falseExpr ← getFalseExpr
   let natZeroExpr ← getNatZeroExpr
-  let thmMap ← getEMatchTheorems
+  let thmMap := params.ematch
   GoalM.run' { mvarId, thmMap } do
     mkENodeCore falseExpr (interpreted := true) (ctor := false) (generation := 0)
     mkENodeCore trueExpr (interpreted := true) (ctor := false) (generation := 0)
     mkENodeCore natZeroExpr (interpreted := true) (ctor := false) (generation := 0)
+    for thm in params.extra do
+      activateTheorem thm 0
 
-private def initCore (mvarId : MVarId) : GrindM (List Goal) := do
+private def initCore (mvarId : MVarId) (params : Params) : GrindM (List Goal) := do
   mvarId.ensureProp
   -- TODO: abstract metavars
   mvarId.ensureNoMVar
@@ -65,13 +81,13 @@ private def initCore (mvarId : MVarId) : GrindM (List Goal) := do
   let mvarId ← mvarId.unfoldReducible
   let mvarId ← mvarId.betaReduce
   appendTagSuffix mvarId `grind
-  let goals ← intros (← mkGoal mvarId) (generation := 0)
+  let goals ← intros (← mkGoal mvarId params) (generation := 0)
   goals.forM (·.checkInvariants (expensive := true))
   return goals.filter fun goal => !goal.inconsistent
 
-def main (mvarId : MVarId) (config : Grind.Config) (mainDeclName : Name) (fallback : Fallback) : MetaM (List Goal) := do
+def main (mvarId : MVarId) (params : Params) (mainDeclName : Name) (fallback : Fallback) : MetaM (List Goal) := do
   let go : GrindM (List Goal) := do
-    let goals ← initCore mvarId
+    let goals ← initCore mvarId params
     let goals ← solve goals
     let goals ← goals.filterMapM fun goal => do
       if goal.inconsistent then return none
@@ -81,6 +97,6 @@ def main (mvarId : MVarId) (config : Grind.Config) (mainDeclName : Name) (fallba
       return some goal
     trace[grind.debug.final] "{← ppGoals goals}"
     return goals
-  go.run mainDeclName config fallback
+  go.run mainDeclName params fallback
 
 end Lean.Meta.Grind

src/Lean/Meta/Tactic/Grind/Parser.lean

@@ -12,4 +12,8 @@ Builtin parsers for `grind` related commands
 -/
 @[builtin_command_parser] def grindPattern := leading_parser
   "grind_pattern " >>  ident >> darrow >> sepBy1 termParser ","
+
+@[builtin_command_parser] def initGrindNorm := leading_parser
+  "init_grind_norm " >> many ident >> "| " >> many ident
+
 end Lean.Parser.Command

src/Lean/Meta/Tactic/Grind/Propagate.lean

@@ -8,6 +8,7 @@ import Init.Grind
 import Lean.Meta.Tactic.Grind.Proof
 import Lean.Meta.Tactic.Grind.PropagatorAttr
 import Lean.Meta.Tactic.Grind.Simp
+import Lean.Meta.Tactic.Grind.Ext
 import Lean.Meta.Tactic.Grind.Internalize
 
 namespace Lean.Meta.Grind
@@ -133,6 +134,19 @@ builtin_grind_propagator propagateEqDown ↓Eq := fun e => do
   if (← isEqTrue e) then
     let_expr Eq _ a b := e | return ()
     pushEq a b <| mkOfEqTrueCore e (← mkEqTrueProof e)
+  else if (← isEqFalse e) then
+    let_expr Eq α lhs rhs := e | return ()
+    let thms ← getExtTheorems α
+    if !thms.isEmpty then
+      /-
+      Heuristic for lists: If `lhs` or `rhs` are contructors we do not apply extensionality theorems.
+      For example, we don't want to apply the extensionality theorem to things like `xs ≠ []`.
+      TODO: polish this hackish heuristic later.
+      -/
+      if α.isAppOf ``List && ((← getRootENode lhs).ctor || (← getRootENode rhs).ctor) then
+        return ()
+      for thm in (← getExtTheorems α) do
+        instantiateExtTheorem thm e
 
 /-- Propagates `EqMatch` downwards -/
 builtin_grind_propagator propagateEqMatchDown ↓Grind.EqMatch := fun e => do

src/Lean/Meta/Tactic/Grind/SimpUtil.lean

@@ -7,18 +7,44 @@ prelude
 import Lean.Meta.Tactic.Simp.Simproc
 import Lean.Meta.Tactic.Grind.Simp
 import Lean.Meta.Tactic.Grind.DoNotSimp
+import Lean.Meta.Tactic.Simp.BuiltinSimprocs.List
 
 namespace Lean.Meta.Grind
 
+builtin_initialize normExt : SimpExtension ← mkSimpExt
+
+def registerNormTheorems (preDeclNames : Array Name) (postDeclNames : Array Name) : MetaM Unit := do
+  let thms ← normExt.getTheorems
+  unless thms.lemmaNames.isEmpty do
+    throwError "`grind` normalization theorems have already been initialized"
+  for declName in preDeclNames do
+    addSimpTheorem normExt declName (post := false) (inv := false) .global (eval_prio default)
+  for declName in postDeclNames do
+    addSimpTheorem normExt declName (post := true) (inv := false) .global (eval_prio default)
+
 /-- Returns the array of simprocs used by `grind`. -/
 protected def getSimprocs : MetaM (Array Simprocs) := do
-  let s ← grindNormSimprocExt.getSimprocs
-  let s ← addDoNotSimp s
-  return #[s, (← Simp.getSEvalSimprocs)]
+  let e ← Simp.getSEvalSimprocs
+  /-
+  We don't want to apply `List.reduceReplicate` as a normalization operation in
+  `grind`. Consider the following example:
+  ```
+  example (ys : List α) : n = 0 → List.replicate n ys = [] := by
+    grind only [List.replicate]
+  ```
+  The E-matching module generates the following instance for `List.replicate.eq_1`
+  ```
+  List.replicate 0 [] = []
+  ```
+  We don't want it to be simplified to `[] = []`.
+  -/
+  let e := e.erase ``List.reduceReplicate
+  let e ← addDoNotSimp e
+  return #[e]
 
 /-- Returns the simplification context used by `grind`. -/
 protected def getSimpContext : MetaM Simp.Context := do
-  let thms ← grindNormExt.getTheorems
+  let thms ← normExt.getTheorems
   Simp.mkContext
     (config := { arith := true })
     (simpTheorems := #[thms])

src/Lean/Meta/Tactic/Grind/Types.lean

@@ -13,6 +13,7 @@ import Lean.Meta.CongrTheorems
 import Lean.Meta.AbstractNestedProofs
 import Lean.Meta.Tactic.Simp.Types
 import Lean.Meta.Tactic.Util
+import Lean.Meta.Tactic.Ext
 import Lean.Meta.Tactic.Grind.ENodeKey
 import Lean.Meta.Tactic.Grind.Attr
 import Lean.Meta.Tactic.Grind.Arith.Types
@@ -395,6 +396,8 @@ structure Goal where
   users when `grind` fails.
   -/
   issues     : List MessageData := []
+  /-- Cached extensionality theorems for types. -/
+  extThms    : PHashMap ENodeKey (Array Ext.ExtTheorem) := {}
   deriving Inhabited
 
 def Goal.admit (goal : Goal) : MetaM Unit :=
@@ -498,8 +501,9 @@ def getENode (e : Expr) : GoalM ENode := do
   (← get).getENode e
 
 /-- Returns the generation of the given term. Is assumes it has been internalized -/
-def getGeneration (e : Expr) : GoalM Nat :=
-  return (← getENode e).generation
+def getGeneration (e : Expr) : GoalM Nat := do
+  let some n ← getENode? e | return 0
+  return n.generation
 
 /-- Returns `true` if `e` is in the equivalence class of `True`. -/
 def isEqTrue (e : Expr) : GoalM Bool := do
@@ -516,8 +520,8 @@ def isEqv (a b : Expr) : GoalM Bool := do
   if isSameExpr a b then
     return true
   else
-    let na ← getENode a
-    let nb ← getENode b
+    let some na ← getENode? a | return false
+    let some nb ← getENode? b | return false
     return isSameExpr na.root nb.root
 
 /-- Returns `true` if the root of its equivalence class. -/
@@ -546,6 +550,11 @@ def getRoot (e : Expr) : GoalM Expr := do
 def getRootENode (e : Expr) : GoalM ENode := do
   getENode (← getRoot e)
 
+/-- Returns the root enode in the equivalence class of `e` if it is in an equivalence class. -/
+def getRootENode? (e : Expr) : GoalM (Option ENode) := do
+  let some n ← getENode? e | return none
+  getENode? n.root
+
 /--
 Returns the next element in the equivalence class of `e`
 if `e` has been internalized in the given goal.
@@ -611,7 +620,7 @@ Records that `parent` is a parent of `child`. This function actually stores the
 information in the root (aka canonical representative) of `child`.
 -/
 def registerParent (parent : Expr) (child : Expr) : GoalM Unit := do
-  let some childRoot ← getRoot? child | return ()
+  let childRoot := (← getRoot? child).getD child
   let parents := if let some parents := (← get).parents.find? { expr := childRoot } then parents else {}
   modify fun s => { s with parents := s.parents.insert { expr := childRoot } (parents.insert parent) }
 
@@ -625,12 +634,10 @@ def getParents (e : Expr) : GoalM ParentSet := do
   return parents
 
 /--
-Similar to `getParents`, but also removes the entry `e ↦ parents` from the parent map.
+Removes the entry `e ↦ parents` from the parent map.
 -/
-def getParentsAndReset (e : Expr) : GoalM ParentSet := do
-  let parents ← getParents e
+def resetParentsOf (e : Expr) : GoalM Unit := do
   modify fun s => { s with parents := s.parents.erase { expr := e } }
-  return parents
 
 /--
 Copy `parents` to the parents of `root`.
@@ -797,6 +804,18 @@ def getENodes : GoalM (Array ENode) := do
     if isSameExpr n.next e then return ()
     curr := n.next
 
+/-- Folds using `f` and `init` over the equivalence class containing `e` -/
+@[inline] def foldEqc (e : Expr) (init : α) (f : ENode → α → GoalM α) : GoalM α := do
+  let mut curr := e
+  let mut r := init
+  repeat
+    let n ← getENode curr
+    r ← f n r
+    if isSameExpr n.next e then return r
+    curr := n.next
+  unreachable!
+  return r
+
 def forEachENode (f : ENode → GoalM Unit) : GoalM Unit := do
   let nodes ← getENodes
   for n in nodes do
@@ -886,4 +905,25 @@ def markCaseSplitAsResolved (e : Expr) : GoalM Unit := do
     trace_goal[grind.split.resolved] "{e}"
     modify fun s => { s with resolvedSplits := s.resolvedSplits.insert { expr := e } }
 
+/--
+Returns extensionality theorems for the given type if available.
+If `Config.ext` is `false`, the result is `#[]`.
+-/
+def getExtTheorems (type : Expr) : GoalM (Array Ext.ExtTheorem) := do
+  unless (← getConfig).ext do return #[]
+  if let some thms := (← get).extThms.find? { expr := type } then
+    return thms
+  else
+    let thms ← Ext.getExtTheorems type
+    modify fun s => { s with extThms := s.extThms.insert { expr := type } thms }
+    return thms
+
+/--
+Helper function for instantiating a type class `type`, and
+then using the result to perform `isDefEq x val`.
+-/
+def synthesizeInstanceAndAssign (x type : Expr) : MetaM Bool := do
+  let .some val ← trySynthInstance type | return false
+  isDefEq x val
+
 end Lean.Meta.Grind

src/Lean/Meta/Tactic/Simp/Diagnostics.lean

@@ -52,12 +52,12 @@ def reportDiag (diag : Simp.Diagnostics) : MetaM Unit := do
     let congr ← mkDiagSummary `simp diag.congrThmCounter
     let thmsWithBadKeys ← mkTheoremsWithBadKeySummary diag.thmsWithBadKeys
     unless used.isEmpty && tried.isEmpty && congr.isEmpty && thmsWithBadKeys.isEmpty do
-      let m := MessageData.nil
+      let m := #[]
       let m := appendSection m `simp "used theorems" used
       let m := appendSection m `simp "tried theorems" tried
       let m := appendSection m `simp "tried congruence theorems" congr
       let m := appendSection m `simp "theorems with bad keys" thmsWithBadKeys (resultSummary := false)
-      let m := m ++ "use `set_option diagnostics.threshold <num>` to control threshold for reporting counters"
-      logInfo m
+      let m := m.push <| "use `set_option diagnostics.threshold <num>` to control threshold for reporting counters"
+      logInfo <| .trace { cls := `simp, collapsed := false } "Diagnostics" m
 
 end Lean.Meta.Simp

src/Lean/Meta/WHNF.lean

@@ -104,7 +104,7 @@ Otherwise executes `failK`.
 -- ===========================
 
 private def getFirstCtor (d : Name) : MetaM (Option Name) := do
-  let some (ConstantInfo.inductInfo { ctors := ctor::_, ..}) ← getUnfoldableConstNoEx? d |
+  let some (ConstantInfo.inductInfo { ctors := ctor::_, ..}) := (← getEnv).find? d |
     return none
   return some ctor
 
@@ -258,7 +258,7 @@ private def reduceQuotRec (recVal  : QuotVal) (recArgs : Array Expr) (failK : Un
       let major ← whnf major
       match major with
       | Expr.app (Expr.app (Expr.app (Expr.const majorFn _) _) _) majorArg => do
-        let some (ConstantInfo.quotInfo { kind := QuotKind.ctor, .. }) ← getUnfoldableConstNoEx? majorFn | failK ()
+        let some (ConstantInfo.quotInfo { kind := QuotKind.ctor, .. }) := (← getEnv).find? majorFn | failK ()
         let f := recArgs[argPos]!
         let r := mkApp f majorArg
         let recArity := majorPos + 1
@@ -321,7 +321,7 @@ mutual
         | .mvar mvarId => return some mvarId
         | _ => getStuckMVar? e
       | .const fName _ =>
-        match (← getUnfoldableConstNoEx? fName) with
+        match (← getEnv).find? fName with
         | some <| .recInfo recVal  => isRecStuck? recVal e.getAppArgs
         | some <| .quotInfo recVal => isQuotRecStuck? recVal e.getAppArgs
         | _  =>
@@ -625,17 +625,18 @@ where
           | .partialApp   => pure e
           | .stuck _      => pure e
           | .notMatcher   =>
-            matchConstAux f' (fun _ => return e) fun cinfo lvls =>
-              match cinfo with
-              | .recInfo rec    => reduceRec rec lvls e.getAppArgs (fun _ => return e) (fun e => do recordUnfold cinfo.name; go e)
-              | .quotInfo rec   => reduceQuotRec rec e.getAppArgs (fun _ => return e) (fun e => do recordUnfold cinfo.name; go e)
-              | c@(.defnInfo _) => do
-                if (← isAuxDef c.name) then
-                  recordUnfold c.name
-                  deltaBetaDefinition c lvls e.getAppRevArgs (fun _ => return e) go
-                else
-                  return e
-              | _ => return e
+            let .const cname lvls := f' | return e
+            let some cinfo := (← getEnv).find? cname | return e
+            match cinfo with
+            | .recInfo rec    => reduceRec rec lvls e.getAppArgs (fun _ => return e) (fun e => do recordUnfold cinfo.name; go e)
+            | .quotInfo rec   => reduceQuotRec rec e.getAppArgs (fun _ => return e) (fun e => do recordUnfold cinfo.name; go e)
+            | c@(.defnInfo _) => do
+              if (← isAuxDef c.name) then
+                recordUnfold c.name
+                deltaBetaDefinition c lvls e.getAppRevArgs (fun _ => return e) go
+              else
+                return e
+            | _ => return e
       | .proj _ i c =>
         let k (c : Expr) := do
           match (← projectCore? c i) with
@@ -860,7 +861,9 @@ def reduceRecMatcher? (e : Expr) : MetaM (Option Expr) := do
     return none
   else match (← reduceMatcher? e) with
     | .reduced e => return e
-    | _ => matchConstAux e.getAppFn (fun _ => pure none) fun cinfo lvls => do
+    | _ =>
+      let .const cname lvls := e.getAppFn | return none
+      let some cinfo := (← getEnv).find? cname | return none
       match cinfo with
       | .recInfo «rec»  => reduceRec «rec» lvls e.getAppArgs (fun _ => pure none) (fun e => do recordUnfold cinfo.name; pure (some e))
       | .quotInfo «rec» => reduceQuotRec «rec» e.getAppArgs (fun _ => pure none) (fun e => do recordUnfold cinfo.name; pure (some e))

src/Lean/Modifiers.lean

@@ -5,6 +5,7 @@ Authors: Leonardo de Moura
 -/
 prelude
 import Lean.Environment
+import Lean.PrivateName
 
 namespace Lean
 
@@ -16,69 +17,12 @@ def addProtected (env : Environment) (n : Name) : Environment :=
 def isProtected (env : Environment) (n : Name) : Bool :=
   protectedExt.isTagged env n
 
-/-! # Private name support.
-
-   Suppose the user marks as declaration `n` as private. Then, we create
-   the name: `_private.<module_name>.0 ++ n`.
-   We say `_private.<module_name>.0` is the "private prefix"
-
-   We assume that `n` is a valid user name and does not contain
-   `Name.num` constructors. Thus, we can easily convert from
-   private internal name to the user given name.
--/
-
-def privateHeader : Name := `_private
-
 def mkPrivateName (env : Environment) (n : Name) : Name :=
   Name.mkNum (privateHeader ++ env.mainModule) 0 ++ n
 
-def isPrivateName : Name → Bool
-  | n@(.str p _) => n == privateHeader || isPrivateName p
-  | .num p _     => isPrivateName p
-  | _            => false
-
-@[export lean_is_private_name]
-def isPrivateNameExport (n : Name) : Bool :=
-  isPrivateName n
-
-/--
-Return `true` if `n` is of the form `_private.<module_name>.0`
-See comment above.
--/
-def isPrivatePrefix (n : Name) : Bool :=
-  match n with
-  | .num p 0 => go p
-  | _ => false
-where
-  go (n : Name) : Bool :=
-    n == privateHeader ||
-    match n with
-    | .str p _ => go p
-    | _ => false
-
-private def privateToUserNameAux (n : Name) : Name :=
-  match n with
-  | .str p s => .str (privateToUserNameAux p) s
-  | .num p i => if isPrivatePrefix n then .anonymous else .num (privateToUserNameAux p) i
-  | _        => .anonymous
-
-@[export lean_private_to_user_name]
-def privateToUserName? (n : Name) : Option Name :=
-  if isPrivateName n then privateToUserNameAux n
-  else none
-
 def isPrivateNameFromImportedModule (env : Environment) (n : Name) : Bool :=
   match privateToUserName? n with
   | some userName => mkPrivateName env userName != n
   | _ => false
 
-private def privatePrefixAux : Name → Name
-  | .str p _ => privatePrefixAux p
-  | n        => n
-
-@[export lean_private_prefix]
-def privatePrefix? (n : Name) : Option Name :=
-  if isPrivateName n then privatePrefixAux n
-  else none
-
 end Lean

src/Lean/PrivateName.lean

@@ -0,0 +1,75 @@
+/-
+Copyright (c) 2019 Microsoft Corporation. All rights reserved.
+Released under Apache 2.0 license as described in the file LICENSE.
+Authors: Leonardo de Moura
+-/
+prelude
+import Init.Notation
+
+namespace Lean
+
+/-! # Private name support.
+
+   Suppose the user marks as declaration `n` as private. Then, we create
+   the name: `_private.<module_name>.0 ++ n`.
+   We say `_private.<module_name>.0` is the "private prefix"
+
+   We assume that `n` is a valid user name and does not contain
+   `Name.num` constructors. Thus, we can easily convert from
+   private internal name to the user given name.
+-/
+
+def privateHeader : Name := `_private
+
+def mkPrivateNameCore (mainModule : Name) (n : Name) : Name :=
+  Name.mkNum (privateHeader ++ mainModule) 0 ++ n
+
+def isPrivateName : Name → Bool
+  | n@(.str p _) => n == privateHeader || isPrivateName p
+  | .num p _     => isPrivateName p
+  | _            => false
+
+@[export lean_is_private_name]
+def isPrivateNameExport (n : Name) : Bool :=
+  isPrivateName n
+
+/--
+Return `true` if `n` is of the form `_private.<module_name>.0`
+See comment above.
+-/
+def isPrivatePrefix (n : Name) : Bool :=
+  match n with
+  | .num p 0 => go p
+  | _ => false
+where
+  go (n : Name) : Bool :=
+    n == privateHeader ||
+    match n with
+    | .str p _ => go p
+    | _ => false
+
+private def privateToUserNameAux (n : Name) : Name :=
+  match n with
+  | .str p s => .str (privateToUserNameAux p) s
+  | .num p i => if isPrivatePrefix n then .anonymous else .num (privateToUserNameAux p) i
+  | _        => .anonymous
+
+@[export lean_private_to_user_name]
+def privateToUserName? (n : Name) : Option Name :=
+  if isPrivateName n then privateToUserNameAux n
+  else none
+
+def privateToUserName (n : Name) : Name :=
+  if isPrivateName n then privateToUserNameAux n
+  else n
+
+private def privatePrefixAux : Name → Name
+  | .str p _ => privatePrefixAux p
+  | n        => n
+
+@[export lean_private_prefix]
+def privatePrefix? (n : Name) : Option Name :=
+  if isPrivateName n then privatePrefixAux n
+  else none
+
+end Lean

src/Lean/Replay.lean

@@ -49,15 +49,13 @@ def isTodo (name : Name) : M Bool := do
   else
     return false
 
-/-- Use the current `Environment` to throw a `KernelException`. -/
-def throwKernelException (ex : KernelException) : M Unit := do
-    let ctx := { fileName := "", options := ({} : KVMap), fileMap := default }
-    let state := { env := (← get).env }
-    Prod.fst <$> (Lean.Core.CoreM.toIO · ctx state) do Lean.throwKernelException ex
+/-- Use the current `Environment` to throw a `Kernel.Exception`. -/
+def throwKernelException (ex : Kernel.Exception) : M Unit := do
+  throw <| .userError <| (← ex.toMessageData {} |>.toString)
 
-/-- Add a declaration, possibly throwing a `KernelException`. -/
+/-- Add a declaration, possibly throwing a `Kernel.Exception`. -/
 def addDecl (d : Declaration) : M Unit := do
-  match (← get).env.addDecl {} d with
+  match (← get).env.addDeclCore 0 d (cancelTk? := none) with
   | .ok env => modify fun s => { s with env := env }
   | .error ex => throwKernelException ex
 

src/Std/Tactic/BVDecide/LRAT/Internal/Clause.lean

@@ -74,9 +74,6 @@ instance [Clause α β] : Entails α β where
 instance [Clause α β] (p : α → Bool) (c : β) : Decidable (p ⊨ c) :=
   inferInstanceAs (Decidable (Clause.eval p c = true))
 
-instance [Clause α β] : Inhabited β where
-  default := empty
-
 end Clause
 
 /--

src/kernel/environment.cpp

@@ -19,16 +19,9 @@ Author: Leonardo de Moura
 
 namespace lean {
 extern "C" object* lean_environment_add(object*, object*);
-extern "C" object* lean_mk_empty_environment(uint32, object*);
 extern "C" object* lean_environment_find(object*, object*);
-extern "C" uint32 lean_environment_trust_level(object*);
 extern "C" object* lean_environment_mark_quot_init(object*);
 extern "C" uint8 lean_environment_quot_init(object*);
-extern "C" object* lean_register_extension(object*);
-extern "C" object* lean_get_extension(object*, object*);
-extern "C" object* lean_set_extension(object*, object*, object*);
-extern "C" object* lean_environment_set_main_module(object*, object*);
-extern "C" object* lean_environment_main_module(object*);
 extern "C" object* lean_kernel_record_unfold (object*, object*);
 extern "C" object* lean_kernel_get_diag(object*);
 extern "C" object* lean_kernel_set_diag(object*, object*);
@@ -62,14 +55,6 @@ environment scoped_diagnostics::update(environment const & env) const {
         return env;
 }
 
-environment mk_empty_environment(uint32 trust_lvl) {
-    return get_io_result<environment>(lean_mk_empty_environment(trust_lvl, io_mk_world()));
-}
-
-environment::environment(unsigned trust_lvl):
-    object_ref(mk_empty_environment(trust_lvl)) {
-}
-
 diagnostics environment::get_diag() const {
     return diagnostics(lean_kernel_get_diag(to_obj_arg()));
 }
@@ -78,18 +63,6 @@ environment environment::set_diag(diagnostics const & diag) const {
     return environment(lean_kernel_set_diag(to_obj_arg(), diag.to_obj_arg()));
 }
 
-void environment::set_main_module(name const & n) {
-    m_obj = lean_environment_set_main_module(m_obj, n.to_obj_arg());
-}
-
-name environment::get_main_module() const {
-    return name(lean_environment_main_module(to_obj_arg()));
-}
-
-unsigned environment::trust_lvl() const {
-    return lean_environment_trust_level(to_obj_arg());
-}
-
 bool environment::is_quot_initialized() const {
     return lean_environment_quot_init(to_obj_arg()) != 0;
 }
@@ -297,7 +270,7 @@ environment environment::add(declaration const & d, bool check) const {
 }
 /*
 addDeclCore (env : Environment) (maxHeartbeats : USize) (decl : @& Declaration)
-  (cancelTk? : @& Option IO.CancelToken) : Except KernelException Environment
+  (cancelTk? : @& Option IO.CancelToken) : Except Kernel.Exception Environment
 */
 extern "C" LEAN_EXPORT object * lean_add_decl(object * env, size_t max_heartbeat, object * decl,
     object * opt_cancel_tk) {
@@ -321,12 +294,6 @@ void environment::for_each_constant(std::function<void(constant_info const & d)>
         });
 }
 
-extern "C" obj_res lean_display_stats(obj_arg env, obj_arg w);
-
-void environment::display_stats() const {
-    dec_ref(lean_display_stats(to_obj_arg(), io_mk_world()));
-}
-
 void initialize_environment() {
 }
 

src/kernel/environment.h

@@ -24,10 +24,6 @@ Author: Leonardo de Moura
 #endif
 
 namespace lean {
-class environment_extension {
-public:
-    virtual ~environment_extension() {}
-};
 
 /* Wrapper for `Kernel.Diagnostics` */
 class diagnostics : public object_ref {
@@ -41,7 +37,7 @@ public:
 };
 
 /*
-Store `Kernel.Diagnostics` stored in environment extension in `m_diag` IF
+Store `Kernel.Diagnostics` (to be stored in `Kernel.Environment.diagnostics`) in `m_diag` IF
 - `Kernel.Diagnostics.enable = true`
 - `collect = true`. This is a minor optimization.
 
@@ -59,6 +55,7 @@ public:
     diagnostics * get() const { return m_diag; }
 };
 
+/* Wrapper for `Lean.Kernel.Environment` */
 class LEAN_EXPORT environment : public object_ref {
     friend class add_inductive_fn;
 
@@ -76,7 +73,6 @@ class LEAN_EXPORT environment : public object_ref {
     environment add_quot() const;
     environment add_inductive(declaration const & d) const;
 public:
-    environment(unsigned trust_lvl = 0);
     environment(environment const & other):object_ref(other) {}
     environment(environment && other):object_ref(other) {}
     explicit environment(b_obj_arg o, bool b):object_ref(o, b) {}
@@ -89,15 +85,8 @@ public:
     diagnostics get_diag() const;
     environment set_diag(diagnostics const & diag) const;
 
-    /** \brief Return the trust level of this environment. */
-    unsigned trust_lvl() const;
-
     bool is_quot_initialized() const;
 
-    void set_main_module(name const & n);
-
-    name get_main_module() const;
-
     /** \brief Return information for the constant with name \c n (if it is defined in this environment). */
     optional<constant_info> find(name const & n) const;
 
@@ -114,8 +103,6 @@ public:
     friend bool is_eqp(environment const & e1, environment const & e2) {
         return e1.raw() == e2.raw();
     }
-
-    void display_stats() const;
 };
 
 void check_no_metavar_no_fvar(environment const & env, name const & n, expr const & e);

src/kernel/kernel_exception.h

@@ -152,9 +152,9 @@ public:
 /*
 Helper function for interfacing C++ code with code written in Lean.
 It executes closure `f` which produces an object_ref of type `A` and may throw
-an `kernel_exception` or `exception`. Then, convert result into `Except KernelException T`
+an `kernel_exception` or `exception`. Then, convert result into `Except Kernel.Exception T`
 where `T` is the type of the lean objected represented by `A`.
-We use the constructor `KernelException.other <msg>` to handle C++ `exception` objects which
+We use the constructor `Kernel.Exception.other <msg>` to handle C++ `exception` objects which
 are not `kernel_exception`.
 */
 template<typename A>

src/kernel/trace.cpp

@@ -8,7 +8,7 @@ Author: Leonardo de Moura
 #include <string>
 #include "util/io.h"
 #include "util/option_declarations.h"
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 #include "kernel/local_ctx.h"
 #include "kernel/trace.h"
 
@@ -17,7 +17,7 @@ static name_set *            g_trace_classes = nullptr;
 static name_map<name_set>  * g_trace_aliases = nullptr;
 MK_THREAD_LOCAL_GET_DEF(std::vector<name>, get_enabled_trace_classes);
 MK_THREAD_LOCAL_GET_DEF(std::vector<name>, get_disabled_trace_classes);
-LEAN_THREAD_PTR(environment,           g_env);
+LEAN_THREAD_PTR(elab_environment,      g_env);
 LEAN_THREAD_PTR(options,               g_opts);
 
 void register_trace_class(name const & n, name const & decl_name) {
@@ -90,7 +90,7 @@ bool is_trace_class_enabled(name const & n) {
 }
 
 
-void scope_trace_env::init(environment * env, options * opts) {
+void scope_trace_env::init(elab_environment * env, options * opts) {
     m_enable_sz  = get_enabled_trace_classes().size();
     m_disable_sz = get_disabled_trace_classes().size();
     m_old_env    = g_env;
@@ -111,12 +111,12 @@ void scope_trace_env::init(environment * env, options * opts) {
     g_opts = opts;
 }
 
-scope_trace_env::scope_trace_env(environment const & env, options const & o) {
-    init(const_cast<environment*>(&env), const_cast<options*>(&o));
+scope_trace_env::scope_trace_env(elab_environment const & env, options const & o) {
+    init(const_cast<elab_environment*>(&env), const_cast<options*>(&o));
 }
 
 scope_trace_env::~scope_trace_env() {
-    g_env  = const_cast<environment*>(m_old_env);
+    g_env  = const_cast<elab_environment*>(m_old_env);
     g_opts = const_cast<options*>(m_old_opts);
     get_enabled_trace_classes().resize(m_enable_sz);
     get_disabled_trace_classes().resize(m_disable_sz);
@@ -169,7 +169,7 @@ def pretty (f : Format) (w : Nat := defWidth) (indent : Nat := 0) (column := 0)
 */
 extern "C" object * lean_format_pretty(object * f, object * w, object * i, object * c);
 
-std::string pp_expr(environment const & env, options const & opts, local_ctx const & lctx, expr const & e) {
+std::string pp_expr(elab_environment const & env, options const & opts, local_ctx const & lctx, expr const & e) {
     options o = opts;
     // o = o.update(name{"pp", "proofs"}, true); --
     object_ref fmt = get_io_result<object_ref>(lean_pp_expr(env.to_obj_arg(), lean_mk_metavar_ctx(lean_box(0)), lctx.to_obj_arg(), o.to_obj_arg(),
@@ -178,7 +178,7 @@ std::string pp_expr(environment const & env, options const & opts, local_ctx con
     return str.to_std_string();
 }
 
-std::string pp_expr(environment const & env, options const & opts, expr const & e) {
+std::string pp_expr(elab_environment const & env, options const & opts, expr const & e) {
     local_ctx lctx;
     return pp_expr(env, opts, lctx, e);
 }

src/kernel/trace.h

@@ -7,7 +7,7 @@ Author: Leonardo de Moura
 #pragma once
 #include <memory>
 #include <string>
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 #include "util/options.h"
 #include "util/message_definitions.h"
 
@@ -20,13 +20,13 @@ bool is_trace_class_enabled(name const & n);
 #define lean_is_trace_enabled(CName) (::lean::is_trace_enabled() && ::lean::is_trace_class_enabled(CName))
 
 class scope_trace_env {
-    unsigned                m_enable_sz;
-    unsigned                m_disable_sz;
-    environment const *     m_old_env;
-    options     const *     m_old_opts;
-    void init(environment * env, options * opts);
+    unsigned                 m_enable_sz;
+    unsigned                 m_disable_sz;
+    elab_environment const * m_old_env;
+    options     const *      m_old_opts;
+    void init(elab_environment * env, options * opts);
 public:
-    scope_trace_env(environment const & env, options const & opts);
+    scope_trace_env(elab_environment const & env, options const & opts);
     ~scope_trace_env();
 };
 

src/kernel/type_checker.cpp

@@ -549,7 +549,7 @@ static expr * g_lean_reduce_bool = nullptr;
 static expr * g_lean_reduce_nat  = nullptr;
 
 namespace ir {
-object * run_boxed(environment const & env, options const & opts, name const & fn, unsigned n, object **args);
+object * run_boxed_kernel(environment const & env, options const & opts, name const & fn, unsigned n, object **args);
 }
 
 expr mk_bool_true();
@@ -560,7 +560,7 @@ optional<expr> reduce_native(environment const & env, expr const & e) {
     expr const & arg = app_arg(e);
     if (!is_constant(arg)) return none_expr();
     if (app_fn(e) == *g_lean_reduce_bool) {
-        object * r = ir::run_boxed(env, options(), const_name(arg), 0, nullptr);
+        object * r = ir::run_boxed_kernel(env, options(), const_name(arg), 0, nullptr);
         if (!lean_is_scalar(r)) {
             lean_dec_ref(r);
             throw kernel_exception(env, "type checker failure, unexpected result value for 'Lean.reduceBool'");
@@ -568,7 +568,7 @@ optional<expr> reduce_native(environment const & env, expr const & e) {
         return lean_unbox(r) == 0 ? some_expr(mk_bool_false()) : some_expr(mk_bool_true());
     }
     if (app_fn(e) == *g_lean_reduce_nat) {
-        object * r = ir::run_boxed(env, options(), const_name(arg), 0, nullptr);
+        object * r = ir::run_boxed_kernel(env, options(), const_name(arg), 0, nullptr);
         if (lean_is_scalar(r) || lean_is_mpz(r)) {
             return some_expr(mk_lit(literal(nat(r))));
         } else {
@@ -1193,24 +1193,6 @@ type_checker::~type_checker() {
         delete m_st;
 }
 
-extern "C" LEAN_EXPORT lean_object * lean_kernel_is_def_eq(lean_object * env, lean_object * lctx, lean_object * a, lean_object * b) {
-    return catch_kernel_exceptions<object*>([&]() {
-        return lean_box(type_checker(environment(env), local_ctx(lctx)).is_def_eq(expr(a), expr(b)));
-    });
-}
-
-extern "C" LEAN_EXPORT lean_object * lean_kernel_whnf(lean_object * env, lean_object * lctx, lean_object * a) {
-    return catch_kernel_exceptions<object*>([&]() {
-        return type_checker(environment(env), local_ctx(lctx)).whnf(expr(a)).steal();
-    });
-}
-
-extern "C" LEAN_EXPORT lean_object * lean_kernel_check(lean_object * env, lean_object * lctx, lean_object * a) {
-    return catch_kernel_exceptions<object*>([&]() {
-        return type_checker(environment(env), local_ctx(lctx)).check(expr(a)).steal();
-    });
-}
-
 inline static expr * new_persistent_expr_const(name const & n) {
     expr * e = new expr(mk_const(n));
     mark_persistent(e->raw());

src/kernel/type_checker.h

@@ -9,6 +9,7 @@ Author: Leonardo de Moura
 #include <memory>
 #include <utility>
 #include <algorithm>
+#include "runtime/flet.h"
 #include "util/lbool.h"
 #include "util/name_set.h"
 #include "util/name_generator.h"
@@ -104,6 +105,7 @@ private:
     optional<expr> reduce_pow(expr const & e);
     optional<expr> reduce_nat(expr const & e);
 public:
+    // The following two constructor are used only by the old compiler and should be deleted with it
     type_checker(state & st, local_ctx const & lctx, definition_safety ds = definition_safety::safe);
     type_checker(state & st, definition_safety ds = definition_safety::safe):type_checker(st, local_ctx(), ds) {}
     type_checker(environment const & env, local_ctx const & lctx, diagnostics * diag = nullptr, definition_safety ds = definition_safety::safe);

src/lake/Lake/Load/Lean/Elab.lean

@@ -81,10 +81,10 @@ def elabConfigFile (pkgDir : FilePath) (lakeOpts : NameMap String)
     return s.commandState.env
 
 /--
-`Lean.Environment.add` is now private, but exported as `lean_environment_add`.
-We call it here via `@[extern]` with a mock implementation.
+`Lean.Kernel.Environment.add` is now private, this is an exported helper wrapping it for
+`Lean.Environment`.
 -/
-@[extern "lean_environment_add"]
+@[extern "lake_environment_add"]
 private opaque addToEnv (env : Environment) (_ : ConstantInfo) : Environment
 
 /--

src/library/CMakeLists.txt

@@ -6,4 +6,5 @@ add_library(library OBJECT expr_lt.cpp
   projection.cpp
   aux_recursors.cpp
   profiling.cpp time_task.cpp
-  formatter.cpp)
+  formatter.cpp
+  elab_environment.cpp)

src/library/aux_recursors.cpp

@@ -10,11 +10,11 @@ namespace lean {
 extern "C" uint8 lean_is_aux_recursor(object * env, object * n);
 extern "C" uint8 lean_is_no_confusion(object * env, object * n);
 
-bool is_aux_recursor(environment const & env, name const & r) {
+bool is_aux_recursor(elab_environment const & env, name const & r) {
     return lean_is_aux_recursor(env.to_obj_arg(), r.to_obj_arg());
 }
 
-bool is_no_confusion(environment const & env, name const & r) {
+bool is_no_confusion(elab_environment const & env, name const & r) {
     return lean_is_no_confusion(env.to_obj_arg(), r.to_obj_arg());
 }
 }

src/library/aux_recursors.h

@@ -5,11 +5,11 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 
 namespace lean {
 /** \brief Return true iff \c n is the name of an auxiliary recursor.
     \see add_aux_recursor */
-bool is_aux_recursor(environment const & env, name const & n);
-bool is_no_confusion(environment const & env, name const & n);
+bool is_aux_recursor(elab_environment const & env, name const & n);
+bool is_no_confusion(elab_environment const & env, name const & n);
 }

src/library/class.cpp

@@ -15,9 +15,9 @@ extern "C" uint8 lean_is_out_param(object* e);
 extern "C" uint8 lean_has_out_params(object* env, object* n);
 
 bool is_class_out_param(expr const & e) { return lean_is_out_param(e.to_obj_arg()); }
-bool has_class_out_params(environment const & env, name const & c) { return lean_has_out_params(env.to_obj_arg(), c.to_obj_arg()); }
-bool is_class(environment const & env, name const & c) { return lean_is_class(env.to_obj_arg(), c.to_obj_arg()); }
-bool is_instance(environment const & env, name const & i) { return lean_is_instance(env.to_obj_arg(), i.to_obj_arg()); }
+bool has_class_out_params(elab_environment const & env, name const & c) { return lean_has_out_params(env.to_obj_arg(), c.to_obj_arg()); }
+bool is_class(elab_environment const & env, name const & c) { return lean_is_class(env.to_obj_arg(), c.to_obj_arg()); }
+bool is_instance(elab_environment const & env, name const & i) { return lean_is_instance(env.to_obj_arg(), i.to_obj_arg()); }
 
 static name * g_anonymous_inst_name_prefix = nullptr;
 

src/library/class.h

@@ -6,11 +6,12 @@ Author: Leonardo de Moura
 */
 #pragma once
 #include "library/util.h"
+#include "library/elab_environment.h"
 namespace lean {
 /** \brief Return true iff \c c was declared with \c add_class. */
-bool is_class(environment const & env, name const & c);
+bool is_class(elab_environment const & env, name const & c);
 /** \brief Return true iff \c i was declared with \c add_instance. */
-bool is_instance(environment const & env, name const & i);
+bool is_instance(elab_environment const & env, name const & i);
 
 name const & get_anonymous_instance_prefix();
 name mk_anonymous_inst_name(unsigned idx);
@@ -20,7 +21,7 @@ bool is_anonymous_inst_name(name const & n);
 bool is_class_out_param(expr const & e);
 
 /** \brief Return true iff c is a type class that contains an `outParam` */
-bool has_class_out_params(environment const & env, name const & c);
+bool has_class_out_params(elab_environment const & env, name const & c);
 
 void initialize_class();
 void finalize_class();

src/library/compiler/closed_term_cache.cpp

@@ -5,16 +5,17 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #include "library/util.h"
+#include "library/elab_environment.h"
 
 namespace lean {
 extern "C" object * lean_cache_closed_term_name(object * env, object * e, object * n);
 extern "C" object * lean_get_closed_term_name(object * env, object * e);
 
-optional<name> get_closed_term_name(environment const & env, expr const & e) {
+optional<name> get_closed_term_name(elab_environment const & env, expr const & e) {
     return to_optional<name>(lean_get_closed_term_name(env.to_obj_arg(), e.to_obj_arg()));
 }
 
-environment cache_closed_term_name(environment const & env, expr const & e, name const & n) {
-    return environment(lean_cache_closed_term_name(env.to_obj_arg(), e.to_obj_arg(), n.to_obj_arg()));
+elab_environment cache_closed_term_name(elab_environment const & env, expr const & e, name const & n) {
+    return elab_environment(lean_cache_closed_term_name(env.to_obj_arg(), e.to_obj_arg(), n.to_obj_arg()));
 }
 }

src/library/compiler/closed_term_cache.h

@@ -5,8 +5,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-optional<name> get_closed_term_name(environment const & env, expr const & e);
-environment cache_closed_term_name(environment const & env, expr const & e, name const & n);
+optional<name> get_closed_term_name(elab_environment const & env, expr const & e);
+elab_environment cache_closed_term_name(elab_environment const & env, expr const & e, name const & n);
 }

src/library/compiler/compiler.cpp

@@ -44,19 +44,19 @@ static name get_real_name(name const & n) {
         return n;
 }
 
-static comp_decls to_comp_decls(environment const & env, names const & cs) {
+static comp_decls to_comp_decls(elab_environment const & env, names const & cs) {
     bool allow_opaque = true;
     return map2<comp_decl>(cs, [&](name const & n) {
             return comp_decl(get_real_name(n), env.get(n).get_value(allow_opaque));
         });
 }
 
-static expr eta_expand(environment const & env, expr const & e) {
-    return type_checker(env).eta_expand(e);
+static expr eta_expand(elab_environment const & env, expr const & e) {
+    return type_checker(env.to_kernel_env()).eta_expand(e);
 }
 
 template<typename F>
-comp_decls apply(F && f, environment const & env, comp_decls const & ds) {
+comp_decls apply(F && f, elab_environment const & env, comp_decls const & ds) {
     return map(ds, [&](comp_decl const & d) { return comp_decl(d.fst(), f(env, d.snd())); });
 }
 
@@ -75,7 +75,7 @@ void trace_comp_decls(comp_decls const & ds) {
     }
 }
 
-static environment cache_stage1(environment env, comp_decls const & ds) {
+static elab_environment cache_stage1(elab_environment env, comp_decls const & ds) {
     for (comp_decl const & d : ds) {
         name n = d.fst();
         expr v = d.snd();
@@ -94,7 +94,7 @@ static expr ensure_arity(expr const & t, unsigned arity) {
     return update_binding(t, binding_domain(t), ensure_arity(binding_body(t), arity-1));
 }
 
-static environment cache_stage2(environment env, comp_decls const & ds, bool only_new_ones = false) {
+static elab_environment cache_stage2(elab_environment env, comp_decls const & ds, bool only_new_ones = false) {
     buffer<expr> ts;
     ll_infer_type(env, ds, ts);
     lean_assert(ts.size() == length(ds));
@@ -116,11 +116,11 @@ static environment cache_stage2(environment env, comp_decls const & ds, bool onl
 }
 
 /* Cache the declarations in `ds` that have not already been cached. */
-static environment cache_new_stage2(environment env, comp_decls const & ds) {
+static elab_environment cache_new_stage2(elab_environment env, comp_decls const & ds) {
     return cache_stage2(env, ds, true);
 }
 
-bool is_main_fn(environment const & env, name const & n) {
+bool is_main_fn(elab_environment const & env, name const & n) {
     if (n == "main") return true;
     if (optional<name> c = get_export_name_for(env, n)) {
         return *c == "main";
@@ -160,15 +160,15 @@ bool is_main_fn_type(expr const & type) {
 
 extern "C" object* lean_csimp_replace_constants(object* env, object* n);
 
-expr csimp_replace_constants(environment const & env, expr const & e) {
+expr csimp_replace_constants(elab_environment const & env, expr const & e) {
     return expr(lean_csimp_replace_constants(env.to_obj_arg(), e.to_obj_arg()));
 }
 
-bool is_matcher(environment const & env, comp_decls const & ds) {
+bool is_matcher(elab_environment const & env, comp_decls const & ds) {
     return length(ds) == 1 && is_matcher(env, head(ds).fst());
 }
 
-environment compile(environment const & env, options const & opts, names cs) {
+elab_environment compile(elab_environment const & env, options const & opts, names cs) {
     /* Do not generate code for irrelevant decls */
     cs = filter(cs, [&](name const & c) { return !is_irrelevant_type(env, env.get(c).get_type());});
     if (empty(cs)) return env;
@@ -202,8 +202,8 @@ environment compile(environment const & env, options const & opts, names cs) {
     csimp_cfg cfg(opts);
     // Use the following line to see compiler intermediate steps
     // scope_traces_as_string trace_scope;
-    auto simp  = [&](environment const & env, expr const & e) { return csimp(env, e, cfg); };
-    auto esimp = [&](environment const & env, expr const & e) { return cesimp(env, e, cfg); };
+    auto simp  = [&](elab_environment const & env, expr const & e) { return csimp(env, e, cfg); };
+    auto esimp = [&](elab_environment const & env, expr const & e) { return cesimp(env, e, cfg); };
     trace_compiler(name({"compiler", "input"}), ds);
     ds = apply(eta_expand, env, ds);
     trace_compiler(name({"compiler", "eta_expand"}), ds);
@@ -218,7 +218,7 @@ environment compile(environment const & env, options const & opts, names cs) {
     ds = apply(simp, env, ds);
     trace_compiler(name({"compiler", "simp"}), ds);
     // trace(ds);
-    environment new_env = env;
+    elab_environment new_env = env;
     std::tie(new_env, ds) = eager_lambda_lifting(new_env, ds, cfg);
     trace_compiler(name({"compiler", "eager_lambda_lifting"}), ds);
     ds = apply(max_sharing, ds);
@@ -274,8 +274,8 @@ environment compile(environment const & env, options const & opts, names cs) {
 }
 
 extern "C" LEAN_EXPORT object * lean_compile_decls(object * env, object * opts, object * decls) {
-    return catch_kernel_exceptions<environment>([&]() {
-            return compile(environment(env), options(opts, true), names(decls, true));
+    return catch_kernel_exceptions<elab_environment>([&]() {
+            return compile(elab_environment(env), options(opts, true), names(decls, true));
         });
 }
 

src/library/compiler/compiler.h

@@ -5,10 +5,10 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-environment compile(environment const & env, options const & opts, names cs);
-inline environment compile(environment const & env, options const & opts, name const & c) {
+elab_environment compile(elab_environment const & env, options const & opts, names cs);
+inline elab_environment compile(elab_environment const & env, options const & opts, name const & c) {
     return compile(env, opts, names(c));
 }
 void initialize_compiler();

src/library/compiler/cse.cpp

@@ -8,7 +8,7 @@ Author: Leonardo de Moura
 #include <vector>
 #include "runtime/flet.h"
 #include "util/name_generator.h"
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 #include "kernel/instantiate.h"
 #include "kernel/abstract.h"
 #include "kernel/for_each_fn.h"
@@ -21,7 +21,7 @@ namespace lean {
 static name * g_cse_fresh = nullptr;
 
 class cse_fn {
-    environment       m_env;
+    elab_environment  m_env;
     name_generator    m_ngen;
     bool              m_before_erasure;
     expr_map<expr>    m_map;
@@ -148,14 +148,14 @@ public:
     }
 
 public:
-    cse_fn(environment const & env, bool before_erasure):
+    cse_fn(elab_environment const & env, bool before_erasure):
         m_env(env), m_ngen(*g_cse_fresh), m_before_erasure(before_erasure) {
     }
 
     expr operator()(expr const & e) { return visit(e); }
 };
 
-expr cse_core(environment const & env, expr const & e, bool before_erasure) {
+expr cse_core(elab_environment const & env, expr const & e, bool before_erasure) {
     return cse_fn(env, before_erasure)(e);
 }
 
@@ -170,6 +170,7 @@ expr cse_core(environment const & env, expr const & e, bool before_erasure) {
    ```
    The "else"-branch is duplicated by the equation compiler for each constructor different from `expr.app`. */
 class cce_fn {
+    elab_environment    m_env;
     type_checker::state m_st;
     local_ctx           m_lctx;
     buffer<expr>        m_fvars;
@@ -178,7 +179,7 @@ class cce_fn {
     name                m_j;
     unsigned            m_next_idx{1};
 public:
-    environment & env() { return m_st.env(); }
+    elab_environment & env() { return m_env; }
 
     name_generator & ngen() { return m_st.ngen(); }
 
@@ -394,8 +395,8 @@ public:
     }
 
 public:
-    cce_fn(environment const & env, local_ctx const & lctx):
-        m_st(env), m_lctx(lctx), m_j("_j") {
+    cce_fn(elab_environment const & env, local_ctx const & lctx):
+        m_env(env), m_st(env), m_lctx(lctx), m_j("_j") {
     }
 
     expr operator()(expr const & e) {
@@ -404,7 +405,7 @@ public:
     }
 };
 
-expr cce_core(environment const & env, local_ctx const & lctx, expr const & e) {
+expr cce_core(elab_environment const & env, local_ctx const & lctx, expr const & e) {
     return cce_fn(env, lctx)(e);
 }
 

src/library/compiler/cse.h

@@ -5,15 +5,15 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
 /* Common subexpression elimination */
-expr cse_core(environment const & env, expr const & e, bool before_erasure);
-inline expr cse(environment const & env, expr const & e) { return cse_core(env, e, true); }
-inline expr ecse(environment const & env, expr const & e) { return cse_core(env, e, false); }
+expr cse_core(elab_environment const & env, expr const & e, bool before_erasure);
+inline expr cse(elab_environment const & env, expr const & e) { return cse_core(env, e, true); }
+inline expr ecse(elab_environment const & env, expr const & e) { return cse_core(env, e, false); }
 /* Common case elimination */
-expr cce_core(environment const & env, local_ctx const & lctx, expr const & e);
-inline expr cce(environment const & env, expr const & e) { return cce_core(env, local_ctx(), e); }
+expr cce_core(elab_environment const & env, local_ctx const & lctx, expr const & e);
+inline expr cce(elab_environment const & env, expr const & e) { return cce_core(env, local_ctx(), e); }
 void initialize_cse();
 void finalize_cse();
 }

src/library/compiler/csimp.cpp

@@ -64,6 +64,7 @@ optional<expr> fold_bin_op(bool before_erasure, expr const & f, expr const & a,
 
 class csimp_fn {
     typedef expr_pair_struct_map<expr> jp_cache;
+    elab_environment         m_env;
     type_checker::state      m_st;
     local_ctx                m_lctx;
     bool                     m_before_erasure;
@@ -96,7 +97,7 @@ class csimp_fn {
     typedef rb_expr_map<expr> expr2ctor;
     expr2ctor                m_expr2ctor;
 
-    environment const & env() const { return m_st.env(); }
+    elab_environment const & env() const { return m_env; }
 
     name_generator & ngen() { return m_st.ngen(); }
 
@@ -1625,12 +1626,12 @@ class csimp_fn {
     }
 
     struct is_recursive_fn {
-        environment const & m_env;
+        elab_environment const & m_env;
         csimp_cfg const &   m_cfg;
         bool                m_before_erasure;
         name                m_target;
 
-        is_recursive_fn(environment const & env, csimp_cfg const & cfg, bool before_erasure):
+        is_recursive_fn(elab_environment const & env, csimp_cfg const & cfg, bool before_erasure):
             m_env(env), m_cfg(cfg), m_before_erasure(before_erasure) {
         }
 
@@ -1969,8 +1970,8 @@ class csimp_fn {
     }
 
 public:
-    csimp_fn(environment const & env, local_ctx const & lctx, bool before_erasure, csimp_cfg const & cfg):
-        m_st(env), m_lctx(lctx), m_before_erasure(before_erasure), m_cfg(cfg), m_x("_x"), m_j("j") {}
+    csimp_fn(elab_environment const & env, local_ctx const & lctx, bool before_erasure, csimp_cfg const & cfg):
+        m_env(env), m_st(env), m_lctx(lctx), m_before_erasure(before_erasure), m_cfg(cfg), m_x("_x"), m_j("j") {}
 
     expr operator()(expr const & e) {
         if (is_lambda(e)) {
@@ -1992,7 +1993,7 @@ bool at_most_once(expr const & e, name const & x) {
 
 /* Eliminate join-points that are used only once */
 class elim_jp1_fn {
-    environment const & m_env;
+    elab_environment const & m_env;
     local_ctx           m_lctx;
     bool                m_before_erasure;
     name_generator      m_ngen;
@@ -2093,7 +2094,7 @@ class elim_jp1_fn {
     }
 
 public:
-    elim_jp1_fn(environment const & env, local_ctx const & lctx, bool before_erasure):
+    elim_jp1_fn(elab_environment const & env, local_ctx const & lctx, bool before_erasure):
         m_env(env), m_lctx(lctx), m_before_erasure(before_erasure) {}
     expr operator()(expr const & e) {
         m_expanded = false;
@@ -2103,7 +2104,7 @@ public:
     bool expanded() const { return m_expanded; }
 };
 
-expr csimp_core(environment const & env, local_ctx const & lctx, expr const & e0, bool before_erasure, csimp_cfg const & cfg) {
+expr csimp_core(elab_environment const & env, local_ctx const & lctx, expr const & e0, bool before_erasure, csimp_cfg const & cfg) {
     csimp_fn simp(env, lctx, before_erasure, cfg);
     elim_jp1_fn elim_jp1(env, lctx, before_erasure);
     expr e = e0;

src/library/compiler/csimp.h

@@ -5,7 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
 struct csimp_cfg {
     /* If `m_inline` == false, then we will not inline `c` even if it is marked with the attribute `[inline]`. */
@@ -23,11 +23,11 @@ public:
     csimp_cfg();
 };
 
-expr csimp_core(environment const & env, local_ctx const & lctx, expr const & e, bool before_erasure, csimp_cfg const & cfg);
-inline expr csimp(environment const & env, expr const & e, csimp_cfg const & cfg = csimp_cfg()) {
+expr csimp_core(elab_environment const & env, local_ctx const & lctx, expr const & e, bool before_erasure, csimp_cfg const & cfg);
+inline expr csimp(elab_environment const & env, expr const & e, csimp_cfg const & cfg = csimp_cfg()) {
     return csimp_core(env, local_ctx(), e, true, cfg);
 }
-inline expr cesimp(environment const & env, expr const & e, csimp_cfg const & cfg = csimp_cfg()) {
+inline expr cesimp(elab_environment const & env, expr const & e, csimp_cfg const & cfg = csimp_cfg()) {
     return csimp_core(env, local_ctx(), e, false, cfg);
 }
 }

src/library/compiler/eager_lambda_lifting.cpp

@@ -98,6 +98,7 @@ static bool depends_on_fvar(local_ctx const & lctx, buffer<expr> const & params,
    Remark: we also skip this transformation for definitions marked as `[inline]` or `[instance]`.
 */
 class eager_lambda_lifting_fn {
+    elab_environment    m_env;
     type_checker::state m_st;
     csimp_cfg           m_cfg;
     local_ctx           m_lctx;
@@ -108,7 +109,7 @@ class eager_lambda_lifting_fn {
     name_set            m_nonterminal_lambdas;
     unsigned            m_next_idx{1};
 
-    environment const & env() const { return m_st.env(); }
+    elab_environment const & env() const { return m_env; }
 
     name_generator & ngen() { return m_st.ngen(); }
 
@@ -234,12 +235,13 @@ class eager_lambda_lifting_fn {
             }
             expr type = cheap_beta_reduce(type_checker(m_st).infer(code));
             name n    = next_name();
-            /* We add the auxiliary declaration `n` as a "meta" axiom to the environment.
+            /* We add the auxiliary declaration `n` as a "meta" axiom to the elab_environment.
                This is a hack to make sure we can use `csimp` to simplify `code` and
                other definitions that use `n`.
                We used a similar hack at `specialize.cpp`. */
             declaration aux_ax = mk_axiom(n, names(), type, true /* meta */);
-            m_st.env() = env().add(aux_ax, false);
+            m_env = m_env.add(aux_ax, false);
+            m_st.env() = m_env;
             m_new_decls.push_back(comp_decl(n, code));
             return mk_app(mk_constant(n), new_params);
         } catch (exception &) {
@@ -398,10 +400,10 @@ class eager_lambda_lifting_fn {
     }
 
 public:
-    eager_lambda_lifting_fn(environment const & env, csimp_cfg const & cfg):
-        m_st(env), m_cfg(cfg) {}
+    eager_lambda_lifting_fn(elab_environment const & env, csimp_cfg const & cfg):
+        m_env(env), m_st(env), m_cfg(cfg) {}
 
-    pair<environment, comp_decls> operator()(comp_decl const & cdecl) {
+    pair<elab_environment, comp_decls> operator()(comp_decl const & cdecl) {
         m_base_name = cdecl.fst();
         expr r = visit(cdecl.snd(), true);
         comp_decl new_cdecl(cdecl.fst(), r);
@@ -410,7 +412,7 @@ public:
     }
 };
 
-pair<environment, comp_decls> eager_lambda_lifting(environment env, comp_decls const & ds, csimp_cfg const & cfg) {
+pair<elab_environment, comp_decls> eager_lambda_lifting(elab_environment env, comp_decls const & ds, csimp_cfg const & cfg) {
     comp_decls r;
     for (comp_decl const & d : ds) {
         if (has_inline_attribute(env, d.fst()) || is_instance(env, d.fst())) {

src/library/compiler/eager_lambda_lifting.h

@@ -5,11 +5,11 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 #include "library/compiler/csimp.h"
 namespace lean {
 /** \brief Eager version of lambda lifting. See comment at eager_lambda_lifting.cpp. */
-pair<environment, comp_decls> eager_lambda_lifting(environment env, comp_decls const & ds, csimp_cfg const & cfg);
+pair<elab_environment, comp_decls> eager_lambda_lifting(elab_environment env, comp_decls const & ds, csimp_cfg const & cfg);
 /* Return true iff `fn` is the name of an auxiliary function generated by `eager_lambda_lifting`. */
 bool is_elambda_lifting_name(name fn);
 };

src/library/compiler/erase_irrelevant.cpp

@@ -16,6 +16,7 @@ Author: Leonardo de Moura
 namespace lean {
 class erase_irrelevant_fn {
     typedef std::tuple<name, expr, expr> let_entry;
+    elab_environment     m_env;
     type_checker::state  m_st;
     local_ctx            m_lctx;
     buffer<expr>         m_let_fvars;
@@ -24,7 +25,7 @@ class erase_irrelevant_fn {
     unsigned             m_next_idx{1};
     expr_map<bool>       m_irrelevant_cache;
 
-    environment & env() { return m_st.env(); }
+    elab_environment & env() { return m_env; }
 
     name_generator & ngen() { return m_st.ngen(); }
 
@@ -485,14 +486,14 @@ class erase_irrelevant_fn {
         lean_unreachable();
     }
 public:
-    erase_irrelevant_fn(environment const & env, local_ctx const & lctx):
-        m_st(env), m_lctx(lctx), m_x("_x") {}
+    erase_irrelevant_fn(elab_environment const & env, local_ctx const & lctx):
+        m_env(env), m_st(env), m_lctx(lctx), m_x("_x") {}
     expr operator()(expr const & e) {
         return mk_let(0, visit(e));
     }
 };
 
-expr erase_irrelevant_core(environment const & env, local_ctx const & lctx, expr const & e) {
+expr erase_irrelevant_core(elab_environment const & env, local_ctx const & lctx, expr const & e) {
     return erase_irrelevant_fn(env, lctx)(e);
 }
 }

src/library/compiler/erase_irrelevant.h

@@ -5,8 +5,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-expr erase_irrelevant_core(environment const & env, local_ctx const & lctx, expr const & e);
-inline expr erase_irrelevant(environment const & env, expr const & e) { return erase_irrelevant_core(env, local_ctx(), e); }
+expr erase_irrelevant_core(elab_environment const & env, local_ctx const & lctx, expr const & e);
+inline expr erase_irrelevant(elab_environment const & env, expr const & e) { return erase_irrelevant_core(env, local_ctx(), e); }
 }

src/library/compiler/export_attribute.cpp

@@ -6,10 +6,11 @@ Author: Leonardo de Moura
 */
 #include "library/constants.h"
 #include "library/util.h"
+#include "library/elab_environment.h"
 
 namespace lean {
 extern "C" object* lean_get_export_name_for(object* env, object *n);
-optional<name> get_export_name_for(environment const & env, name const & n) {
+optional<name> get_export_name_for(elab_environment const & env, name const & n) {
     return to_optional<name>(lean_get_export_name_for(env.to_obj_arg(), n.to_obj_arg()));
 }
 }

src/library/compiler/export_attribute.h

@@ -5,8 +5,8 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-optional<name> get_export_name_for(environment const & env, name const & n);
-inline bool has_export_name(environment const & env, name const & n) { return static_cast<bool>(get_export_name_for(env, n)); }
+optional<name> get_export_name_for(elab_environment const & env, name const & n);
+inline bool has_export_name(elab_environment const & env, name const & n) { return static_cast<bool>(get_export_name_for(env, n)); }
 }

src/library/compiler/extern_attribute.cpp

@@ -23,15 +23,15 @@ Authors: Leonardo de Moura
 namespace lean {
 extern "C" object* lean_get_extern_attr_data(object* env, object* n);
 
-optional<extern_attr_data_value> get_extern_attr_data(environment const & env, name const & fn) {
+optional<extern_attr_data_value> get_extern_attr_data(elab_environment const & env, name const & fn) {
     return to_optional<extern_attr_data_value>(lean_get_extern_attr_data(env.to_obj_arg(), fn.to_obj_arg()));
 }
 
-bool is_extern_constant(environment const & env, name const & c) {
+bool is_extern_constant(elab_environment const & env, name const & c) {
     return static_cast<bool>(get_extern_attr_data(env, c));
 }
 
-bool is_extern_or_init_constant(environment const & env, name const & c) {
+bool is_extern_or_init_constant(elab_environment const & env, name const & c) {
     if (is_extern_constant(env, c)) {
         return true;
     } else if (auto info = env.find(c)) {
@@ -44,7 +44,7 @@ bool is_extern_or_init_constant(environment const & env, name const & c) {
 
 extern "C" object * lean_get_extern_const_arity(object* env, object*, object* w);
 
-optional<unsigned> get_extern_constant_arity(environment const & env, name const & c) {
+optional<unsigned> get_extern_constant_arity(elab_environment const & env, name const & c) {
     auto arity = get_io_result<option_ref<nat>>(lean_get_extern_const_arity(env.to_obj_arg(), c.to_obj_arg(), lean_io_mk_world()));
     if (optional<nat> aux = arity.get()) {
         return optional<unsigned>(aux->get_small_value());
@@ -53,7 +53,7 @@ optional<unsigned> get_extern_constant_arity(environment const & env, name const
     }
 }
 
-bool get_extern_borrowed_info(environment const & env, name const & c, buffer<bool> & borrowed_args, bool & borrowed_res) {
+bool get_extern_borrowed_info(elab_environment const & env, name const & c, buffer<bool> & borrowed_args, bool & borrowed_res) {
     if (is_extern_constant(env, c)) {
         /* Extract borrowed info from type */
         expr type = env.get(c).get_type();
@@ -80,7 +80,7 @@ bool get_extern_borrowed_info(environment const & env, name const & c, buffer<bo
     return false;
 }
 
-optional<expr> get_extern_constant_ll_type(environment const & env, name const & c) {
+optional<expr> get_extern_constant_ll_type(elab_environment const & env, name const & c) {
     if (is_extern_or_init_constant(env, c)) {
         unsigned arity = 0;
         expr type = env.get(c).get_type();

src/library/compiler/extern_attribute.h

@@ -6,15 +6,15 @@ Authors: Leonardo de Moura
 */
 #pragma once
 #include <string>
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-bool is_extern_constant(environment const & env, name const & c);
-bool is_extern_or_init_constant(environment const & env, name const & c);
-optional<expr> get_extern_constant_ll_type(environment const & env, name const & c);
-optional<unsigned> get_extern_constant_arity(environment const & env, name const & c);
+bool is_extern_constant(elab_environment const & env, name const & c);
+bool is_extern_or_init_constant(elab_environment const & env, name const & c);
+optional<expr> get_extern_constant_ll_type(elab_environment const & env, name const & c);
+optional<unsigned> get_extern_constant_arity(elab_environment const & env, name const & c);
 typedef object_ref extern_attr_data_value;
-optional<extern_attr_data_value> get_extern_attr_data(environment const & env, name const & c);
+optional<extern_attr_data_value> get_extern_attr_data(elab_environment const & env, name const & c);
 /* Return true if `c` is an extern constant, and store in borrowed_args and
    borrowed_res which arguments/results are marked as borrowed. */
-bool get_extern_borrowed_info(environment const & env, name const & c, buffer<bool> & borrowed_args, bool & borrowed_res);
+bool get_extern_borrowed_info(elab_environment const & env, name const & c, buffer<bool> & borrowed_args, bool & borrowed_res);
 }

src/library/compiler/extract_closed.cpp

@@ -25,7 +25,7 @@ bool is_extract_closed_aux_fn(name const & n) {
 }
 
 class extract_closed_fn {
-    environment         m_env;
+    elab_environment    m_env;
     comp_decls          m_input_decls;
     name_generator      m_ngen;
     local_ctx           m_lctx;
@@ -34,7 +34,7 @@ class extract_closed_fn {
     unsigned            m_next_idx{1};
     expr_map<bool>      m_closed;
 
-    environment const & env() const { return m_env; }
+    elab_environment const & env() const { return m_env; }
     name_generator & ngen() { return m_ngen; }
 
     name next_name() {
@@ -286,11 +286,11 @@ class extract_closed_fn {
     }
 
 public:
-    extract_closed_fn(environment const & env, comp_decls const & ds):
+    extract_closed_fn(elab_environment const & env, comp_decls const & ds):
         m_env(env), m_input_decls(ds) {
     }
 
-    pair<environment, comp_decls> operator()(comp_decl const & d) {
+    pair<elab_environment, comp_decls> operator()(comp_decl const & d) {
         if (arity_was_reduced(d)) {
             /* Do nothing since `d` will be inlined. */
             return mk_pair(env(), comp_decls(d));
@@ -308,11 +308,11 @@ public:
     }
 };
 
-pair<environment, comp_decls> extract_closed_core(environment const & env, comp_decls const & input_ds, comp_decl const & d) {
+pair<elab_environment, comp_decls> extract_closed_core(elab_environment const & env, comp_decls const & input_ds, comp_decl const & d) {
     return extract_closed_fn(env, input_ds)(d);
 }
 
-pair<environment, comp_decls> extract_closed(environment env, comp_decls const & ds) {
+pair<elab_environment, comp_decls> extract_closed(elab_environment env, comp_decls const & ds) {
     comp_decls r;
     for (comp_decl const & d : ds) {
         comp_decls new_ds;

src/library/compiler/extract_closed.h

@@ -5,9 +5,9 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 #include "library/compiler/util.h"
 namespace lean {
 bool is_extract_closed_aux_fn(name const & n);
-pair<environment, comp_decls> extract_closed(environment env, comp_decls const & ds);
+pair<elab_environment, comp_decls> extract_closed(elab_environment env, comp_decls const & ds);
 }

src/library/compiler/find_jp.cpp

@@ -13,7 +13,7 @@ namespace lean {
 
 /* Find join-points */
 class find_jp_fn {
-    environment const & m_env;
+    elab_environment const & m_env;
     local_ctx           m_lctx;
     name_generator      m_ngen;
     name_map<unsigned>  m_candidates;
@@ -130,7 +130,7 @@ class find_jp_fn {
     }
 
 public:
-    find_jp_fn(environment const & env):
+    find_jp_fn(elab_environment const & env):
         m_env(env) {}
 
     expr operator()(expr const & e) {
@@ -138,7 +138,7 @@ public:
     }
 };
 
-expr find_jp(environment const & env, expr const & e) {
+expr find_jp(elab_environment const & env, expr const & e) {
     return find_jp_fn(env)(e);
 }
 }

src/library/compiler/find_jp.h

@@ -5,7 +5,7 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
-expr find_jp(environment const & env, expr const & e);
+expr find_jp(elab_environment const & env, expr const & e);
 }

src/library/compiler/implemented_by_attribute.cpp

@@ -4,11 +4,11 @@ Released under Apache 2.0 license as described in the file LICENSE.
 
 Author: Leonardo de Moura
 */
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 namespace lean {
 extern "C" object* lean_get_implemented_by(object*, object*);
 
-optional<name> get_implemented_by_attribute(environment const & env, name const & n) {
+optional<name> get_implemented_by_attribute(elab_environment const & env, name const & n) {
     return to_optional<name>(lean_get_implemented_by(env.to_obj_arg(), n.to_obj_arg()));
 }
 }

src/library/compiler/implemented_by_attribute.h

@@ -5,11 +5,11 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Author: Leonardo de Moura
 */
 #pragma once
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 
 namespace lean {
-optional<name> get_implemented_by_attribute(environment const & env, name const & n);
-inline bool has_implemented_by_attribute(environment const & env, name const & n) {
+optional<name> get_implemented_by_attribute(elab_environment const & env, name const & n);
+inline bool has_implemented_by_attribute(elab_environment const & env, name const & n) {
     return static_cast<bool>(get_implemented_by_attribute(env, n));
 }
 }

src/library/compiler/init_attribute.cpp

@@ -5,12 +5,12 @@ Released under Apache 2.0 license as described in the file LICENSE.
 Authors: Leonardo de Moura
 */
 #include "runtime/object_ref.h"
-#include "kernel/environment.h"
+#include "library/elab_environment.h"
 
 namespace lean {
 extern "C" object* lean_get_init_fn_name_for(object* env, object* fn);
 
-optional<name> get_init_fn_name_for(environment const & env, name const & n) {
+optional<name> get_init_fn_name_for(elab_environment const & env, name const & n) {
     return to_optional<name>(lean_get_init_fn_name_for(env.to_obj_arg(), n.to_obj_arg()));
 }
 }